import java.io.IOException;
import java.io.InputStream;
import java.util.*;

public class Main {
    public static void main(String[] args){
       int n = sc.nextInt();
       String s = sc.next();
       int white = 0;
       while (white<n&&s.charAt(white)=='.')white++;
       int black = n-1;
       while (black>=0&&s.charAt(black)=='#')black--;
       if ((white==0&&black==-1)||(white==n&&black==n-1))System.out.println(0);
       else {
           int tot = black-white+1;
           int w = 0;
           for (int i=white;i<=black;i++)if (s.charAt(i)=='.')w++;
           System.out.println(Math.min(w,tot-w));
       }
    }
    public static int popCount(int num){
        int n = num;
        int count = 0;
        while (n!=0){
            count+=n%2;
            n/=2;
        }
        return count;
    }
    public static int function(int num){
        int n = num;
        int count = 0;
        while (n!=0){
            count++;
            n%=popCount(n);
        }
        return count;
    }
    public static long MOD = 1000000007;
    public static int tenE9 = 1000000000;
    static Basic basic = new Basic();
    static FastScanner sc = new FastScanner();
    public static class FastScanner {
        private final InputStream in = System.in;
        private final byte[] buffer = new byte[1024];
        private int ptr = 0;
        private int buflen = 0;
        private boolean hasNextByte() {
            if (ptr < buflen) {
                return true;
            }else{
                ptr = 0;
                try {
                    buflen = in.read(buffer);
                } catch (IOException e) {
                    e.printStackTrace();
                }
                if (buflen <= 0) {
                    return false;
                }
            }
            return true;
        }
        private int readByte() { if (hasNextByte()) return buffer[ptr++]; else return -1;}
        private static boolean isPrintableChar(int c) { return 33 <= c && c <= 126;}
        public boolean hasNext() { while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++; return hasNextByte();}
        public String next() {
            if (!hasNext()) throw new NoSuchElementException();
            StringBuilder sb = new StringBuilder();
            int b = readByte();
            while(isPrintableChar(b)) {
                sb.appendCodePoint(b);
                b = readByte();
            }
            return sb.toString();
        }
        public long nextLong() {
            if (!hasNext()) throw new NoSuchElementException();
            long n = 0;
            boolean minus = false;
            int b = readByte();
            if (b == '-') {
                minus = true;
                b = readByte();
            }
            if (b < '0' || '9' < b) {
                throw new NumberFormatException();
            }
            while(true){
                if ('0' <= b && b <= '9') {
                    n *= 10;
                    n += b - '0';
                }else if(b == -1 || !isPrintableChar(b)){
                    return minus ? -n : n;
                }else{
                    throw new NumberFormatException();
                }
                b = readByte();
            }
        }
        public int nextInt() {
            long nl = nextLong();
            if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException();
            return (int) nl;
        }
        public double nextDouble() { return Double.parseDouble(next());}
    }
    public static class Basic {
        //math
        private final int MAX = 510000;
        private final long MOD = Main.MOD;
        private final long[] fac = new long[MAX];
        private final long[] finv = new long[MAX];
        private final long[] inv = new long[MAX];
        public long factorial(long num) {
            if (num < 2) return 1;
            else return num * factorial(num - 1);
        }
        public long modFactorial(long num) {
            if (num < 2) return 1;
            else return num*modFactorial(num-1)%MOD;
        }
        public int arraySum(int[] array) {
            int ans = 0;
            for (int value : array) ans += value;
            return ans;
        }
        public double log(double base, double antilogarithm) {
            return Math.log(antilogarithm) / Math.log(base);
        }
        public long gcd(long x, long y) {
            if (y == 0) return x;
            else return gcd(y, x % y);
        }
        public long lcm(long x, long y) {
            return x / gcd(x, y) * y;
        }
        public HashMap<Long, Long> factorization(long num) {
            HashMap<Long, Long> hash = new HashMap<>();
            long n = num;
            long count = 2;
            while (n > 1) {
                while (n % count == 0) {
                    n /= count;
                    if (hash.containsKey(count)) hash.put(count, hash.get(count) + 1);
                    else hash.put(count, 1L);
                }
                count++;
            }
            return hash;
        }
        public int sum(int[] num) {
            int ans = 0;
            for (int i = 0; i < num.length; i++) {
                ans += num[i];
            }
            return ans;
        }
        public int[] reduce(int small, int big) {
            int ins = 2;
            while (ins <= small) {
                if (small % ins == 0 && big % ins == 0) {
                    small /= ins;
                    big /= ins;
                    ins = 2;
                } else {
                    ins++;
                }
            }
            return new int[]{small, big};
        }
        public int reduceCount(int small, int big) {
            int ins = 2;
            int ans = 0;
            while (ins <= small) {
                if (small % ins == 0 && big % ins == 0) {
                    small /= ins;
                    big /= ins;
                    ins = 2;
                    ans++;
                } else {
                    ins++;
                }
            }
            return ans;
        }
        public int binarySearch(int[] array, int target) {
            int pos = -1;
            int left = 0;
            int right = array.length - 1;
            int middle;
            while (pos == -1 && left <= right) {
                middle = (left + right) / 2;
                if (array[middle] == target) pos = middle;
                else if (array[middle] > target) right = middle - 1;
                else left = middle + 1;
            }
            return pos;
        }
        public int upperBound(int[] ar, long d, int n, int f){
            int p = n;
            int q = f;
            while (p-q>1){
                int mid = (p+q)/2;
                if (ar[mid]==d){
                    return mid+1;
                }
                if (ar[mid]<d)q=mid;
                else p=mid;

            }
            return p;
        }
        public long modPow(long a, long n, long mod) {
            long res = 1;
            while (n > 0) {
                if ((n & 1) != 0) res = res * a % mod;
                a = a * a % mod;
                n >>= 1;
            }
            return res;
        }
        public long modinv(long a, long mod) {
            return modPow(a, mod - 2, mod);
        }
        public void COMinit() {
            fac[0] = 1;
            fac[1] = 1;
            finv[0] = 1;
            finv[1] = 1;
            inv[1] = 1;
            for (int i = 2; i < MAX; i++) {
                fac[i] = fac[i - 1] * i % MOD;
                inv[i] = MOD - inv[(int)(MOD % i)] * (MOD / i) % MOD;
                finv[i] = finv[i - 1] * inv[i] % MOD;
            }
        }
        public long COM(int n, int k) {
            if (n < k) return 0;
            if (n < 0 || k < 0) return 0;
            return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
        }
        public long PER(int n, int k){
            return fac[n]*finv[n-k]%MOD;
        }
        public long HCOM(int n, int k) {
            return COM(n + k - 1, k);
        }
        public boolean[] getIsPrimeArray(int max){
            boolean[] ret = new boolean[max+1];
            Arrays.fill(ret,true);
            ret[0]=false;
            ret[1]=false;
            for (int i=2;i<=max;i++){
                if (ret[i]){
                    int c = 2*i;
                    while (c<=max){
                        ret[c]=false;
                        c+=i;
                    }
                }
            }
            return ret;
        }

        //array
        public int[] remove(int[] ar, int pos) {
            int[] ret = new int[ar.length - 1];
            for (int i = 0; i < pos; i++) ret[i] = ar[i];
            for (int i = pos + 1; i < ar.length; i++) ret[i - 1] = ar[i];
            return ret;
        }
        public int[] nextArray(int size,int cons){
            int[] ret = new int[size];
            for (int i=0;i<size;i++)ret[i]=sc.nextInt()+cons;
            return  ret;
        }
        public int[] reverse(int[] ar){
            int[] ret = new int[ar.length];
            for (int i=0;i<ar.length;i++){
                ret[i]=ar[ar.length-1-i];
            }
            return ret;
        }
        public long[] cumulative_sum(int[] ar){
            long[] ret = new long[ar.length+1];
            ret[0]=0;
            for (int i=0;i<ar.length;i++)ret[i+1]=ret[i]+ar[i];
            return ret;
        }
        //graph
        public void warshall_floyd(int[][] d) {
            int n = d.length;
            for (int k = 0; k < n; k++)
                for (int i = 0; i < n; i++) for (int j = 0; j < n; j++) d[i][j] = Math.min(d[i][j], d[i][k] + d[k][j]);
        }//隣接行列が引数。辺が無い場合、INFを入力。
        public int[] bellman_ford(int[][] d, int size, int start){
            int e = d.length;
            int[] ans = new int[size];
            Arrays.fill(ans,Integer.MAX_VALUE);
            ans[start]=0;
            for (int i=0;i<size;i++){
                for (int[] a : d) {
                    if (ans[a[1]] > ans[a[0]] + a[2]) {
                        ans[a[1]] = ans[a[0]] + a[2];
                        if (i == size - 1) {
                            System.out.println("negative loop");
                            break;
                        }
                    }
                }
            }
            return ans;
        }//辺を配列の要素として管理。

    }
    public static class Queue<T>{
        private final int max = 1000000;
        private final T[] queue = (T[]) new Object[max];
        private int tail = 0; private int head = 0;
        public void init(){this.head = 0; tail = 0;}
        public boolean isEmpty(){return (head==tail);}
        public boolean isFull(){return (head == (tail+1)%max);}
        public void enqueue(T v){
            if (isFull()){
                System.out.println("error: queue is full.");
                return;
            }
            queue[tail++] = v;
            if (tail == max) tail = 0;
        }
        public T dequeue(){
            if (isEmpty()){
                System.out.println("error: queue is empty");
                return null;
            }
            T res = queue[head];
            ++head;
            if (head == max) head = 0;
            return res;
        }
    }
    public static class Deque<T>{
        private final int max = 1000000;
        private final T[] queue = (T[]) new Object[max];
        private int tail = 0; private int head = 0;
        public void init(){this.head = 0; tail = 0;}
        public boolean isEmpty(){return (head==tail);}
        public boolean isFull(){return (head == (tail+1)%max);}
        public void pushFirst(T v){
            if (isFull()){
                System.out.println("error: queue is full.");
                return;
            }
            head--;
            if (head==-1)head=max-1;
            queue[head] = v;
        }
        public void pushLast(T v){
            if (isFull()){
                System.out.println("error: queue is full.");
                return;
            }
            queue[tail++] = v;
            if (tail == max) tail = 0;
        }
        public T popFirst(){
            if (isEmpty()){
                System.out.println("error: queue is empty");
                return null;
            }
            T res = queue[head];
            ++head;
            if (head == max) head = 0;
            return res;
        }
        public T popLast(){
            if (isEmpty()){
                System.out.println("error: queue is empty");
                return null;
            }
            if (--tail==-1)tail=max-1;
            return queue[tail];
        }

        public T peekFirst(){
            if (isEmpty()){
                System.out.println("error: queue is empty");
                return null;
            }
            return queue[head];
        }
        public T peekLast(){
            if (isEmpty()){
                System.out.println("error: queue is empty");
                return null;
            }
            return queue[tail];
        }
    }
    public static class Stack<T>{
        private final int max = 100000;
        private final T[] stack =(T[]) new Object[max];
        private int top = 0;
        public boolean isEmpty(){return (top==0);}
        public boolean isFull(){return (top==max);}
        public void init(){top=0;}
        public void push(T v){
            if (isFull()){
                System.out.println("error: stack is full.");
                return;
            }
            stack[top++] = v;
        }
        public T pop(){
            if (isEmpty()){
                System.out.println("error: stack is empty");
                return null;
            }
            return stack[--top];
        }
        public T peek(){
            if (isEmpty()){
                System.out.println("error: stack is empty");
                return null;
            }
            return stack[top];
        }
    }
    public static class Pair<K,V>{
        private K A;
        private V B;
        Pair(K a,V b){
            A=a;
            B=b;
        }
        public void changeA(K a){A=a;}
        public void changeB(V b){B=b;}
        public void changeAB(K a,V b){A=a;B=b;}
        public static Comparator numberSortWithA = new Comparator() {
            @Override
            public int compare(Object o1, Object o2) {
                Pair p = (Pair)o1;
                Pair q = (Pair)o2;
                if ((int)p.A<(int)q.A)return -1;
                else if ((int)p.A==(int)q.A){
                    if ((int)p.B<(int)q.B)return -1;
                    else if ((int)p.B==(int)q.B)return 0;
                    else return 1;
                }
                else return 1;
            }
        };
        public static Comparator numberSortWithB = new Comparator() {
            @Override
            public int compare(Object o1, Object o2) {
                Pair p = (Pair)o1;
                Pair q = (Pair)o2;
                if ((int)p.B<(int)q.B)return -1;
                else if ((int)p.B==(int)q.B){
                    if ((int)p.A<(int)q.A)return -1;
                    else if ((int)p.A==(int)q.A)return 0;
                    else return 1;
                }
                else return 1;
            }
        };
    }
    public static class Graph{
        private final HashMap<Integer,HashSet<Integer>> graph = new HashMap<>();
        private final int Size;
        Graph(int size){
            for (int i=0;i<size;i++)graph.put(i,new HashSet<>());
            Size = size;
        }

        public void addEdge(int node1,int node2){
            if (graph.containsKey(node1)&&graph.containsKey(node2)){
                graph.get(node1).add(node2);
                graph.get(node2).add(node1);
            }
        }
        public void addDirectEdge(int from,int to){
            if (graph.containsKey(from)&&graph.containsKey(to)){
                graph.get(from).add(to);
            }
        }
        public int[] depth(int root){
            Queue<Integer> q = new Queue<>();
            q.enqueue(root);
            boolean[] seen = new boolean[Size];
            Arrays.fill(seen, false);
            seen[root]=true;
            int[] depth = new int[Size];
            depth[root]=0;
            while (!q.isEmpty()){
                int v = q.dequeue();
                for (int u : graph.get(v)){
                    if (!seen[u]){
                        seen[u]=true;
                        q.enqueue(u);
                        depth[u]=depth[v]+1;
                    }
                }
            }
            return depth;
        }
        public HashSet<Integer> getConnected(int pos){return graph.get(pos);}
    }
    public static class WeightedGraph{
        private final HashMap<Integer,HashMap<Integer,Integer>> graph = new HashMap<>();
        private final int Size;
        private long[] Depth;
        WeightedGraph(int size){
            for (int i=0;i<size;i++)graph.put(i,new HashMap<>());
            Size = size;
        }

        public void addEdge(int node1,int node2,int weight){
            if (graph.containsKey(node1)&&graph.containsKey(node2)){
                graph.get(node1).put(node2,weight);
                graph.get(node2).put(node1,weight);
            }
        }
        public void addDirectEdge(int from,int to,int weight){
            if (graph.containsKey(from)&&graph.containsKey(to)){
                graph.get(from).put(to,weight);
            }
        }
        public int[] dijkstra(int root){
            Comparator<int[]> c = new Comparator<int[]>() {
                @Override
                public int compare(int[] o1, int[] o2) {
                    return Integer.compare(o1[1], o2[1]);
                }
            };
            PriorityQueue<int[]> q = new PriorityQueue<>(c);
            q.add(new int[]{root,0});
            int[] ret = new int[Size];
            Arrays.fill(ret,Integer.MAX_VALUE);
            ret[root]=0;
            while (!q.isEmpty()){
                int[] v = q.poll();
                if (v[1]<=ret[v[0]]){
                    HashMap<Integer,Integer> h = graph.get(v[0]);
                    for (int u : h.keySet()){
                        if (ret[u]>v[1]+h.get(u)){
                            ret[u]=v[1]+h.get(u);
                            q.add(new int[]{u,ret[u]});
                        }
                    }
                }
            }
            return ret;
        }

        public long[] Depth(int root){
            Queue<Integer> q = new Queue<>();
            q.enqueue(root);
            boolean[] seen = new boolean[Size];
            Arrays.fill(seen, false);
            seen[root]=true;
            long[] depth = new long[Size];
            depth[root]=0;
            while (!q.isEmpty()){
                int v = q.dequeue();
                for (int u : graph.get(v).keySet()){
                    if (!seen[u]){
                        seen[u]=true;
                        q.enqueue(u);
                        depth[u]=depth[v]+graph.get(v).get(u);
                    }
                }
            }
            Depth = depth.clone();
            return depth;
        }

    }
    public static class UnionFindTree{
        int[] parent;
        int[] rank;
        int[] Size;
        int Number;
        public UnionFindTree(int size){
            this.parent = new int[size];
            this.rank = new int[size];
            this.Size = new int[size];
            makeSet();
        }
        public void makeSet(){
            for (int i=0;i<Size.length;i++){
                parent[i]=i;
                rank[i]=0;
                Size[i]=1;
            }
            Number= Size.length;
        }
        public void unite(int x, int y){
            int xRoot = find(x);
            int yRoot = find(y);
            if (rank[xRoot]>rank[yRoot]){
                parent[yRoot] = xRoot;
                Size[xRoot]+=Size[yRoot];
                Number--;
            }else if (rank[xRoot]<rank[yRoot]){
                parent[xRoot] = yRoot;
                Size[yRoot]+=Size[xRoot];
                Number--;
            }else if (xRoot!=yRoot){
                parent[yRoot] = xRoot;
                rank[xRoot]++;
                Size[xRoot]+=Size[yRoot];
                Number--;
            }
        }
        public int find(int i){
            if (i!= parent[i]){
                parent[i]=find(parent[i]);
            }
            return parent[i];
        }
        public boolean same(int x, int y){
            return find(x) == find(y);
        }
        public int getSize(int i){return Size[find(i)];}
        boolean isConnected(){
            return Number<2;
        }
    }
    public static class BitSearch<T>{
        T[] Array;
        int Width;
        int Length;
        BitSearch(T[] t, int width){
            Array = t;
            Width = width;
            Length = Array.length;
        }
        void start(){
            long max = (long)Math.pow(Width,Length);
            for (long i=0;i<max;i++){
                StringBuilder s = new StringBuilder(Long.toString(i, Width));
                while (s.length()<Length) s.insert(0, "0");
                run(s);
            }
        }
        void run(StringBuilder s){

        }
    }

}


import java.io.IOException;
import java.io.InputStream;
import java.util.*;
import java.util.stream.IntStream;

public class Main {
	public static void main(String[] args) {
		Main main = new Main();
		main.solve();
	}

	private void solve() {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		String S = sc.next();
		boolean black = false;
		int blackCount = 0;
		int ans = 0;
		for (int i = 0; i < N; i++) {
			if (S.charAt(i) == '#') {
				black = true;
				if (i < N - 1) {
					blackCount++;
				}
			}
			if (black && S.charAt(i) == '.') {
				ans++;
			}
		}
		System.out.println(Math.min(ans, blackCount));
	}

	class Scanner {
		private InputStream in;
		private byte[] buffer = new byte[1024];
		private int index;
		private int length;

		public Scanner(InputStream in) {
			this.in = in;
		}

		private boolean isPrintableChar(int c) {
			return '!' <= c && c <= '~';
		}

		private boolean isDigit(int c) {
			return '0' <= c && c <= '9';
		}

		private boolean hasNextByte() {
			if (index < length) {
				return true;
			} else {
				try {
					length = in.read(buffer);
					index = 0;
				} catch (IOException e) {
					e.printStackTrace();
				}
				return length > 0;
			}
		}

		private boolean hasNext() {
			while (hasNextByte() && !isPrintableChar(buffer[index])) {
				index++;
			}
			return hasNextByte();
		}

		private int readByte() {
			return hasNextByte() ? buffer[index++] : -1;
		}

		public String next() {
			if (!hasNext()) {
				throw new RuntimeException("no input");
			}
			StringBuilder sb = new StringBuilder();
			int b = readByte();
			while (isPrintableChar(b)) {
				sb.appendCodePoint(b);
				b = readByte();
			}
			return sb.toString();
		}

		public long nextLong() {
			if (!hasNext()) {
				throw new RuntimeException("no input");
			}
			long value = 0L;
			boolean minus = false;
			int b = readByte();
			if (b == '-') {
				minus = true;
				b = readByte();
			}
			while (isPrintableChar(b)) {
				if (isDigit(b)) {
					value = value * 10 + (b - '0');
				}
				b = readByte();
			}
			return minus ? -value : value;
		}

		public int nextInt() {
			return (int)nextLong();
		}

		public double nextDouble() {
			return Double.parseDouble(next());
		}
	}

	interface CombCalculator {
		long comb(int n, int m);
	}

	interface MobiusFunction {
		int get(int n);
	}

	/**
	 * メビウス関数をエラトステネスの篩っぽく前計算するクラスです。
	 * 計算量はO(1)で、前計算でO(N logN)です。
	 */
	class SieveMobiusFunction implements MobiusFunction {
		int size;
		int[] mobiusFunctionValues;

		public SieveMobiusFunction(int size) {
			this.size = size;
			mobiusFunctionValues = new int[size];

			mobiusFunctionValues[0] = 0;
			mobiusFunctionValues[1] = 1;
			for (int i = 2; i < size; i++) {
				mobiusFunctionValues[i] = 1;
			}
			for (int i = 2; i * i < size; i++) {
				for (int k = 1; i * i * k < size; k++) {
					mobiusFunctionValues[i * i * k] *= 0;
				}
			}

			for (int i = 2; i < size; i++) {
				if (mobiusFunctionValues[i] == 1) {
					for (int k = 1; i * k < size; k++) {
						mobiusFunctionValues[i * k] *= -2;
					}
				}
				if (mobiusFunctionValues[i] > 1) {
					mobiusFunctionValues[i] = 1;
				}
				if (mobiusFunctionValues[i] < -1) {
					mobiusFunctionValues[i] = -1;
				}
			}
		}

		@Override
		public int get(int n) {
			if (n > size) {
				throw new RuntimeException("n is greater than size.");
			}
			if (n < 0) {
				return 0;
			}
			return mobiusFunctionValues[n];
		}
	}

	/**
	 * メビウス関数を定義通り計算するクラスです。
	 * 計算量はO(logN)です。
	 */
	class PrimeFactorizationMobiusFunction implements MobiusFunction {
		@Override
		public int get(int n) {
			if (n <= 0) {
				return 0;
			}
			if (n == 1) {
				return 1;
			}
			int num = 0;
			for (int i = 2; i < n; i++) {
				if (n % i == 0) {
					n /= i;
					num++;
					if (n % i == 0) {
						return 0;
					}
				}
			}
			return num % 2 == 0 ? -1 : 1;
		}
	}

	/**
	 * 組み合わせ計算を階乗の値で行うクラスです(MOD対応)
	 * 階乗とその逆元は前計算してテーブルに格納します。
	 * C(N, N) % M の計算量は O(1)、 前計算でO(max(N, logM))です。
	 * sizeを1e8より大きい値で実行するとMLEの危険性があります。
	 * また素数以外のMODには対応していません(逆元の計算に素数の剰余環の性質を利用しているため)。
	 */
	class FactorialTableCombCalculator implements CombCalculator {
		int size;
		long[] factorialTable;
		long[] inverseFactorialTable;
		long mod;

		public FactorialTableCombCalculator(int size, long mod) {
			this.size = size;
			factorialTable = new long[size + 1];
			inverseFactorialTable = new long[size + 1];
			this.mod = mod;

			factorialTable[0] = 1L;
			for (int i = 1; i <= size; i++) {
				factorialTable[i] = (factorialTable[i - 1] * i) % mod;
			}
			inverseFactorialTable[size] = inverse(factorialTable[size], mod);
			for (int i = size - 1; i >= 0; i--) {
				inverseFactorialTable[i] = (inverseFactorialTable[i + 1] * (i + 1)) % mod;
			}
		}

		private long inverse(long n, long mod) {
			return pow(n, mod - 2, mod);
		}

		private long pow(long n, long p, long mod) {
			if (p == 0) {
				return 1L;
			}
			long half = pow(n, p / 2, mod);
			long ret = (half * half) % mod;
			if (p % 2 == 1) {
				ret = (ret * n) % mod;
			}
			return ret;
		}

		@Override
		public long comb(int n, int m) {
			if (n > size) {
				throw new RuntimeException("n is greater than size.");
			}
			if (n < 0 || m < 0 || n < m) {
				return 0L;
			}
			return (((factorialTable[n] * inverseFactorialTable[m]) % mod) * inverseFactorialTable[n - m]) % mod;
		}
	}

	/**
	 * 組み合わせ計算をテーブルで実装したクラスです(MOD対応)
	 * 前計算でO(N^2), combはO(1)で実行できます
	 * sizeを2 * 1e4より大きい値で実行するとMLEの危険性があります
	 */
	class TableCombCalculator implements CombCalculator {
		long[][] table;
		int size;

		public TableCombCalculator(int size, long mod) {
			this.size = size;
			table = new long[size + 1][];

			table[0] = new long[1];
			table[0][0] = 1L;
			for (int n = 1; n <= size; n++) {
				table[n] = new long[n + 1];
				table[n][0] = 1L;
				for (int m = 1; m < n; m++) {
					table[n][m] = (table[n - 1][m - 1] + table[n - 1][m]) % mod;
				}
				table[n][n] = 1L;
			}
		}

		@Override
		public long comb(int n, int m) {
			if (n > size) {
				throw new RuntimeException("n is greater than size.");
			}
			if (n < 0 || m < 0 || n < m) {
				return 0L;
			}
			return table[n][m];
		}
	}

	interface Graph {
		void link(int from, int to, long cost);
		Optional<Long> getCost(int from, int to);
		int getVertexNum();
	}

	interface FlowResolver {
		long maxFlow(int from, int to);
	}

	/**
	 * グラフの行列による実装
	 * 接点数の大きいグラフで使うとMLEで死にそう
	 */
	class ArrayGraph implements Graph {
		private Long[][] costArray;
		private int vertexNum;

		public ArrayGraph(int n) {
			costArray = new Long[n][];
			for (int i = 0; i < n; i++) {
				costArray[i] = new Long[n];
			}
			vertexNum = n;
		}

		@Override
		public void link(int from, int to, long cost) {
			costArray[from][to] = new Long(cost);
		}

		@Override
		public Optional<Long> getCost(int from, int to) {
			return Optional.ofNullable(costArray[from][to]);
		}

		@Override
		public int getVertexNum() {
			return vertexNum;
		}
	}

	/**
	 * DFS(深さ優先探索)による実装
	 * 計算量はO(E*MaxFlow)のはず (E:辺の数, MaxFlow:最大フロー)
	 */
	class DfsFlowResolver implements FlowResolver {
		private Graph graph;
		public DfsFlowResolver(Graph graph) {
			this.graph = graph;
		}

		/**
		 * 最大フロー(最小カット)を求める
		 * @param from 始点(source)のID
		 * @param to 終点(target)のID
		 * @return 最大フロー(最小カット)
		 */
		public long maxFlow(int from, int to) {
			long sum = 0L;
			long currentFlow;
			do {
				currentFlow = flow(from, to, Long.MAX_VALUE / 3, new boolean[graph.getVertexNum()]);
				sum += currentFlow;
			} while (currentFlow > 0);
			return sum;
		}

		/**
		 * フローの実行 グラフの更新も行う
		 * @param from 現在いる節点のID
		 * @param to 終点(target)のID
		 * @param current_flow ここまでの流量
		 * @param passed 既に通った節点か否かを格納した配列
		 * @return 終点(target)に流した流量/戻りのグラフの流量
		 */
		private long flow(int from, int to, long current_flow, boolean[] passed) {
			passed[from] = true;
			if (from == to) {
				return current_flow;
			}
			for (int id = 0; id < graph.getVertexNum(); id++) {
				if (passed[id]) {
					continue;
				}
				Optional<Long> cost = graph.getCost(from, id);
				if (cost.orElse(0L) > 0) {
					long nextFlow = current_flow < cost.get() ? current_flow : cost.get();
					long returnFlow = flow(id, to, nextFlow, passed);
					if (returnFlow > 0) {
						graph.link(from, id, cost.get() - returnFlow);
						graph.link(id, from, graph.getCost(id, from).orElse(0L) + returnFlow);
						return returnFlow;
					}
				}
			}
			return 0L;
		}
	}

	/**
	 * 1-indexedのBIT配列
	 */
	class BinaryIndexedTree {
		private long[] array;

		public BinaryIndexedTree(int size) {
			this.array = new long[size + 1];
		}

		/**
		 * 指定した要素に値を加算する
		 * 計算量はO(logN)
		 * @param index 加算する要素の添字
		 * @param value 加算する量
		 */
		public void add(int index, long value) {
			for (int i = index; i < array.length; i += (i & -i)) {
				array[i] += value;
			}
		}

		/**
		 * 1〜指定した要素までの和を取得する
		 * 計算量はO(logN)
		 * @param index 和の終端となる要素の添字
		 * @return 1〜indexまでの和
		 */
		public long getSum(int index) {
			long sum = 0L;
			for (int i = index; i > 0; i -= (i & -i)) {
				sum += array[i];
			}
			return sum;
		}
	}

	/**
	 * 1-indexedの2次元BIT配列
	 */
	class BinaryIndexedTree2D {
		private long[][] array;

		public BinaryIndexedTree2D(int size1, int size2) {
			this.array = new long[size1 + 1][];
			for (int i = 1; i <= size1; i++) {
				this.array[i] = new long[size2 + 1];
			}
		}

		/**
		 * 指定した要素に値を加算する
		 * 計算量はO(logN * logN)
		 * @param index1 加算する要素の1次元目の添字
		 * @param index2 加算する要素の2次元目の添字
		 * @param value 加算する量
		 */
		public void add(int index1, int index2, long value) {
			for (int i1 = index1; i1 < array.length; i1 += (i1 & -i1)) {
				for (int i2 = index2; i2 < array.length; i2 += (i2 & -i2)) {
					array[i1][i2] += value;
				}
			}
		}

		/**
		 * (1,1)〜指定した要素までの矩形和を取得する
		 * 計算量はO(logN * logN)
		 * @param index1 和の終端となる要素の1次元目の添字
		 * @param index2 和の終端となる要素の2次元目の添字
		 * @return (1,1)〜(index1,index2)までの矩形和
		 */
		public long getSum(int index1, int index2) {
			long sum = 0L;
			for (int i1 = index1; i1 > 0; i1 -= (i1 & -i1)) {
				for (int i2 = index2; i2 > 0; i2 -= (i2 & -i2)) {
					sum += array[i1][i2];
				}
			}
			return sum;
		}
	}

	interface UnionFind {
		void union(int A, int B);
		boolean judge(int A, int B);
		Set<Integer> getSet(int id);
	}

	/**
	 * ArrayUnionFindの拡張
	 * MapSetで根の添字から根にぶら下がる頂点の集合が取得できるようにした
	 * getSetメソッドをO(logN * logN)に落とせているはず
	 * ただしunionメソッドは2倍の計算量になっているので注意(オーダーは変わらないはず)
	 */
	class SetUnionFind extends ArrayUnionFind {
		Map<Integer, Set<Integer>> map;
		public SetUnionFind(int size) {
			super(size);
			map = new HashMap<>();
			for (int i = 0; i < size; i++) {
				map.put(i, new HashSet<>());
				map.get(i).add(i);
			}
		}

		@Override
		protected void unionTo(int source, int dest) {
			super.unionTo(source, dest);
			map.get(dest).addAll(map.get(source));
		}

		@Override
		public Set<Integer> getSet(int id) {
			return map.get(root(id));
		}
	}

	/**
	 * 配列によるUnionFindの実装
	 * getSetメソッドはO(NlogN)なのでTLEに注意
	 */
	class ArrayUnionFind implements UnionFind {
		int[] parent;
		int[] rank;
		int size;
		public ArrayUnionFind(int size) {
			parent = new int[size];
			for (int i = 0; i < size; i++) {
				parent[i] = i;
			}
			rank = new int[size];
			this.size = size;
		}

		@Override
		public void union(int A, int B) {
			int rootA = root(A);
			int rootB = root(B);
			if (rootA != rootB) {
				if (rank[rootA] < rank[rootB]) {
					unionTo(rootA, rootB);
				} else {
					unionTo(rootB, rootA);
					if (rank[rootA] == rank[rootB]) {
						rank[rootA]++;
					}
				}
			}
		}

		protected void unionTo(int source, int dest) {
			parent[source] = dest;
		}

		@Override
		public boolean judge(int A, int B) {
			return root(A) == root(B);
		}

		@Override
		public Set<Integer> getSet(int id) {
			Set<Integer> set = new HashSet<>();
			IntStream.range(0, size).filter(i -> judge(i, id)).forEach(set::add);
			return set;
		}

		protected int root(int id) {
			if (parent[id] == id) {
				return id;
			}
			parent[id] = root(parent[id]);
			return parent[id];
		}
	}

	/**
	 * 素数のユーティリティ
	 */
	class PrimeNumberUtils {
		boolean[] isPrimeArray;
		List<Integer> primes;

		/**
		 * 素数判定の上限となる値を指定してユーティリティを初期化
		 * @param limit 素数判定の上限(この値以上が素数であるか判定しない)
		 */
		public PrimeNumberUtils(int limit) {
			if (limit > 10000000) {
				System.err.println("上限の値が高すぎるため素数ユーティリティの初期化でTLEする可能性が大変高いです");
			}
			primes = new ArrayList<>();
			isPrimeArray = new boolean[limit];
			if (limit > 2) {
				primes.add(2);
				isPrimeArray[2] = true;
			}

			for (int i = 3; i < limit; i += 2) {
				if (isPrime(i, primes)) {
					primes.add(i);
					isPrimeArray[i] = true;
				}
			}
		}

		public List<Integer> getPrimeNumberList() {
			return primes;
		}

		public boolean isPrime(int n) {
			return isPrimeArray[n];
		}

		private boolean isPrime(int n, List<Integer> primes) {
			for (int prime : primes) {
				if (n % prime == 0) {
					return false;
				}
				if (prime > Math.sqrt(n)) {
					break;
				}
			}
			return true;
		}
	}

	interface BitSet {
		void set(int index, boolean bit);
		boolean get(int index);
		void shiftRight(int num);
		void shiftLeft(int num);
		void or(BitSet bitset);
		void and(BitSet bitset);
	}

	/**
	 * Longの配列によるBitSetの実装
	 * get/setはO(1)
	 * shift/or/andはO(size / 64)
	 */
	class LongBit implements BitSet {
		long[] bitArray;

		public LongBit(int size) {
			bitArray = new long[((size + 63) / 64)];
		}

		@Override
		public void set(int index, boolean bit) {
			int segment = index / 64;
			int inIndex = index % 64;
			if (bit) {
				bitArray[segment] |= 1L << inIndex;
			} else {
				bitArray[segment] &= ~(1L << inIndex);
			}
		}

		@Override
		public boolean get(int index) {
			int segment = index / 64;
			int inIndex = index % 64;
			return (bitArray[segment] & (1L << inIndex)) != 0L;
		}

		@Override
		public void shiftRight(int num) {
			int shiftSeg = num / 64;
			int shiftInI = num % 64;
			for (int segment = 0; segment < bitArray.length; segment++) {
				int sourceSeg = segment + shiftSeg;
				if (sourceSeg < bitArray.length) {
					bitArray[segment] = bitArray[sourceSeg] >>> shiftInI;
					if (shiftInI > 0 && sourceSeg + 1 < bitArray.length) {
						bitArray[segment] |= bitArray[sourceSeg + 1] << (64 - shiftInI);
					}
				} else {
					bitArray[segment] = 0L;
				}
			}
		}

		@Override
		public void shiftLeft(int num) {
			int shiftSeg = num / 64;
			int shiftInI = num % 64;
			for (int segment = bitArray.length - 1; segment >= 0; segment--) {
				int sourceSeg = segment - shiftSeg;
				if (sourceSeg >= 0) {
					bitArray[segment] = bitArray[sourceSeg] << shiftInI;
					if (shiftInI > 0 && sourceSeg > 0) {
						bitArray[segment] |= bitArray[sourceSeg - 1] >>> (64 - shiftInI);
					}
				} else {
					bitArray[segment] = 0L;
				}
			}
		}

		public long getLong(int segment) {
			return bitArray[segment];
		}

		@Override
		public void or(BitSet bitset) {
			if (!(bitset instanceof LongBit)) {
				return;
			}
			for (int segment = 0; segment < bitArray.length; segment++) {
				bitArray[segment] |= ((LongBit)bitset).getLong(segment);
			}
		}

		@Override
		public void and(BitSet bitset) {
			if (!(bitset instanceof LongBit)) {
				return;
			}
			for (int segment = 0; segment < bitArray.length; segment++) {
				bitArray[segment] &= ((LongBit)bitset).getLong(segment);
			}
		}
	}

}


import java.io.IOException;
import java.io.InputStream;
import java.util.*;
import java.util.stream.IntStream;

public class Main {
	public static void main(String[] args) {
		Main main = new Main();
		main.solve();
	}

	private void solve() {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		String S = sc.next();
		boolean black = false;
		int blackCount = 0;
		int ans = 0;
		for (int i = 0; i < N; i++) {
			if (S.charAt(i) == '#') {
				black = true;
				blackCount++;
			}
			if (black && S.charAt(i) == '.') {
				ans++;
			}
		}
		System.out.println(Math.min(ans, blackCount));
	}

	class Scanner {
		private InputStream in;
		private byte[] buffer = new byte[1024];
		private int index;
		private int length;

		public Scanner(InputStream in) {
			this.in = in;
		}

		private boolean isPrintableChar(int c) {
			return '!' <= c && c <= '~';
		}

		private boolean isDigit(int c) {
			return '0' <= c && c <= '9';
		}

		private boolean hasNextByte() {
			if (index < length) {
				return true;
			} else {
				try {
					length = in.read(buffer);
					index = 0;
				} catch (IOException e) {
					e.printStackTrace();
				}
				return length > 0;
			}
		}

		private boolean hasNext() {
			while (hasNextByte() && !isPrintableChar(buffer[index])) {
				index++;
			}
			return hasNextByte();
		}

		private int readByte() {
			return hasNextByte() ? buffer[index++] : -1;
		}

		public String next() {
			if (!hasNext()) {
				throw new RuntimeException("no input");
			}
			StringBuilder sb = new StringBuilder();
			int b = readByte();
			while (isPrintableChar(b)) {
				sb.appendCodePoint(b);
				b = readByte();
			}
			return sb.toString();
		}

		public long nextLong() {
			if (!hasNext()) {
				throw new RuntimeException("no input");
			}
			long value = 0L;
			boolean minus = false;
			int b = readByte();
			if (b == '-') {
				minus = true;
				b = readByte();
			}
			while (isPrintableChar(b)) {
				if (isDigit(b)) {
					value = value * 10 + (b - '0');
				}
				b = readByte();
			}
			return minus ? -value : value;
		}

		public int nextInt() {
			return (int)nextLong();
		}

		public double nextDouble() {
			return Double.parseDouble(next());
		}
	}

	interface CombCalculator {
		long comb(int n, int m);
	}

	interface MobiusFunction {
		int get(int n);
	}

	/**
	 * メビウス関数をエラトステネスの篩っぽく前計算するクラスです。
	 * 計算量はO(1)で、前計算でO(N logN)です。
	 */
	class SieveMobiusFunction implements MobiusFunction {
		int size;
		int[] mobiusFunctionValues;

		public SieveMobiusFunction(int size) {
			this.size = size;
			mobiusFunctionValues = new int[size];

			mobiusFunctionValues[0] = 0;
			mobiusFunctionValues[1] = 1;
			for (int i = 2; i < size; i++) {
				mobiusFunctionValues[i] = 1;
			}
			for (int i = 2; i * i < size; i++) {
				for (int k = 1; i * i * k < size; k++) {
					mobiusFunctionValues[i * i * k] *= 0;
				}
			}

			for (int i = 2; i < size; i++) {
				if (mobiusFunctionValues[i] == 1) {
					for (int k = 1; i * k < size; k++) {
						mobiusFunctionValues[i * k] *= -2;
					}
				}
				if (mobiusFunctionValues[i] > 1) {
					mobiusFunctionValues[i] = 1;
				}
				if (mobiusFunctionValues[i] < -1) {
					mobiusFunctionValues[i] = -1;
				}
			}
		}

		@Override
		public int get(int n) {
			if (n > size) {
				throw new RuntimeException("n is greater than size.");
			}
			if (n < 0) {
				return 0;
			}
			return mobiusFunctionValues[n];
		}
	}

	/**
	 * メビウス関数を定義通り計算するクラスです。
	 * 計算量はO(logN)です。
	 */
	class PrimeFactorizationMobiusFunction implements MobiusFunction {
		@Override
		public int get(int n) {
			if (n <= 0) {
				return 0;
			}
			if (n == 1) {
				return 1;
			}
			int num = 0;
			for (int i = 2; i < n; i++) {
				if (n % i == 0) {
					n /= i;
					num++;
					if (n % i == 0) {
						return 0;
					}
				}
			}
			return num % 2 == 0 ? -1 : 1;
		}
	}

	/**
	 * 組み合わせ計算を階乗の値で行うクラスです(MOD対応)
	 * 階乗とその逆元は前計算してテーブルに格納します。
	 * C(N, N) % M の計算量は O(1)、 前計算でO(max(N, logM))です。
	 * sizeを1e8より大きい値で実行するとMLEの危険性があります。
	 * また素数以外のMODには対応していません(逆元の計算に素数の剰余環の性質を利用しているため)。
	 */
	class FactorialTableCombCalculator implements CombCalculator {
		int size;
		long[] factorialTable;
		long[] inverseFactorialTable;
		long mod;

		public FactorialTableCombCalculator(int size, long mod) {
			this.size = size;
			factorialTable = new long[size + 1];
			inverseFactorialTable = new long[size + 1];
			this.mod = mod;

			factorialTable[0] = 1L;
			for (int i = 1; i <= size; i++) {
				factorialTable[i] = (factorialTable[i - 1] * i) % mod;
			}
			inverseFactorialTable[size] = inverse(factorialTable[size], mod);
			for (int i = size - 1; i >= 0; i--) {
				inverseFactorialTable[i] = (inverseFactorialTable[i + 1] * (i + 1)) % mod;
			}
		}

		private long inverse(long n, long mod) {
			return pow(n, mod - 2, mod);
		}

		private long pow(long n, long p, long mod) {
			if (p == 0) {
				return 1L;
			}
			long half = pow(n, p / 2, mod);
			long ret = (half * half) % mod;
			if (p % 2 == 1) {
				ret = (ret * n) % mod;
			}
			return ret;
		}

		@Override
		public long comb(int n, int m) {
			if (n > size) {
				throw new RuntimeException("n is greater than size.");
			}
			if (n < 0 || m < 0 || n < m) {
				return 0L;
			}
			return (((factorialTable[n] * inverseFactorialTable[m]) % mod) * inverseFactorialTable[n - m]) % mod;
		}
	}

	/**
	 * 組み合わせ計算をテーブルで実装したクラスです(MOD対応)
	 * 前計算でO(N^2), combはO(1)で実行できます
	 * sizeを2 * 1e4より大きい値で実行するとMLEの危険性があります
	 */
	class TableCombCalculator implements CombCalculator {
		long[][] table;
		int size;

		public TableCombCalculator(int size, long mod) {
			this.size = size;
			table = new long[size + 1][];

			table[0] = new long[1];
			table[0][0] = 1L;
			for (int n = 1; n <= size; n++) {
				table[n] = new long[n + 1];
				table[n][0] = 1L;
				for (int m = 1; m < n; m++) {
					table[n][m] = (table[n - 1][m - 1] + table[n - 1][m]) % mod;
				}
				table[n][n] = 1L;
			}
		}

		@Override
		public long comb(int n, int m) {
			if (n > size) {
				throw new RuntimeException("n is greater than size.");
			}
			if (n < 0 || m < 0 || n < m) {
				return 0L;
			}
			return table[n][m];
		}
	}

	interface Graph {
		void link(int from, int to, long cost);
		Optional<Long> getCost(int from, int to);
		int getVertexNum();
	}

	interface FlowResolver {
		long maxFlow(int from, int to);
	}

	/**
	 * グラフの行列による実装
	 * 接点数の大きいグラフで使うとMLEで死にそう
	 */
	class ArrayGraph implements Graph {
		private Long[][] costArray;
		private int vertexNum;

		public ArrayGraph(int n) {
			costArray = new Long[n][];
			for (int i = 0; i < n; i++) {
				costArray[i] = new Long[n];
			}
			vertexNum = n;
		}

		@Override
		public void link(int from, int to, long cost) {
			costArray[from][to] = new Long(cost);
		}

		@Override
		public Optional<Long> getCost(int from, int to) {
			return Optional.ofNullable(costArray[from][to]);
		}

		@Override
		public int getVertexNum() {
			return vertexNum;
		}
	}

	/**
	 * DFS(深さ優先探索)による実装
	 * 計算量はO(E*MaxFlow)のはず (E:辺の数, MaxFlow:最大フロー)
	 */
	class DfsFlowResolver implements FlowResolver {
		private Graph graph;
		public DfsFlowResolver(Graph graph) {
			this.graph = graph;
		}

		/**
		 * 最大フロー(最小カット)を求める
		 * @param from 始点(source)のID
		 * @param to 終点(target)のID
		 * @return 最大フロー(最小カット)
		 */
		public long maxFlow(int from, int to) {
			long sum = 0L;
			long currentFlow;
			do {
				currentFlow = flow(from, to, Long.MAX_VALUE / 3, new boolean[graph.getVertexNum()]);
				sum += currentFlow;
			} while (currentFlow > 0);
			return sum;
		}

		/**
		 * フローの実行 グラフの更新も行う
		 * @param from 現在いる節点のID
		 * @param to 終点(target)のID
		 * @param current_flow ここまでの流量
		 * @param passed 既に通った節点か否かを格納した配列
		 * @return 終点(target)に流した流量/戻りのグラフの流量
		 */
		private long flow(int from, int to, long current_flow, boolean[] passed) {
			passed[from] = true;
			if (from == to) {
				return current_flow;
			}
			for (int id = 0; id < graph.getVertexNum(); id++) {
				if (passed[id]) {
					continue;
				}
				Optional<Long> cost = graph.getCost(from, id);
				if (cost.orElse(0L) > 0) {
					long nextFlow = current_flow < cost.get() ? current_flow : cost.get();
					long returnFlow = flow(id, to, nextFlow, passed);
					if (returnFlow > 0) {
						graph.link(from, id, cost.get() - returnFlow);
						graph.link(id, from, graph.getCost(id, from).orElse(0L) + returnFlow);
						return returnFlow;
					}
				}
			}
			return 0L;
		}
	}

	/**
	 * 1-indexedのBIT配列
	 */
	class BinaryIndexedTree {
		private long[] array;

		public BinaryIndexedTree(int size) {
			this.array = new long[size + 1];
		}

		/**
		 * 指定した要素に値を加算する
		 * 計算量はO(logN)
		 * @param index 加算する要素の添字
		 * @param value 加算する量
		 */
		public void add(int index, long value) {
			for (int i = index; i < array.length; i += (i & -i)) {
				array[i] += value;
			}
		}

		/**
		 * 1〜指定した要素までの和を取得する
		 * 計算量はO(logN)
		 * @param index 和の終端となる要素の添字
		 * @return 1〜indexまでの和
		 */
		public long getSum(int index) {
			long sum = 0L;
			for (int i = index; i > 0; i -= (i & -i)) {
				sum += array[i];
			}
			return sum;
		}
	}

	/**
	 * 1-indexedの2次元BIT配列
	 */
	class BinaryIndexedTree2D {
		private long[][] array;

		public BinaryIndexedTree2D(int size1, int size2) {
			this.array = new long[size1 + 1][];
			for (int i = 1; i <= size1; i++) {
				this.array[i] = new long[size2 + 1];
			}
		}

		/**
		 * 指定した要素に値を加算する
		 * 計算量はO(logN * logN)
		 * @param index1 加算する要素の1次元目の添字
		 * @param index2 加算する要素の2次元目の添字
		 * @param value 加算する量
		 */
		public void add(int index1, int index2, long value) {
			for (int i1 = index1; i1 < array.length; i1 += (i1 & -i1)) {
				for (int i2 = index2; i2 < array.length; i2 += (i2 & -i2)) {
					array[i1][i2] += value;
				}
			}
		}

		/**
		 * (1,1)〜指定した要素までの矩形和を取得する
		 * 計算量はO(logN * logN)
		 * @param index1 和の終端となる要素の1次元目の添字
		 * @param index2 和の終端となる要素の2次元目の添字
		 * @return (1,1)〜(index1,index2)までの矩形和
		 */
		public long getSum(int index1, int index2) {
			long sum = 0L;
			for (int i1 = index1; i1 > 0; i1 -= (i1 & -i1)) {
				for (int i2 = index2; i2 > 0; i2 -= (i2 & -i2)) {
					sum += array[i1][i2];
				}
			}
			return sum;
		}
	}

	interface UnionFind {
		void union(int A, int B);
		boolean judge(int A, int B);
		Set<Integer> getSet(int id);
	}

	/**
	 * ArrayUnionFindの拡張
	 * MapSetで根の添字から根にぶら下がる頂点の集合が取得できるようにした
	 * getSetメソッドをO(logN * logN)に落とせているはず
	 * ただしunionメソッドは2倍の計算量になっているので注意(オーダーは変わらないはず)
	 */
	class SetUnionFind extends ArrayUnionFind {
		Map<Integer, Set<Integer>> map;
		public SetUnionFind(int size) {
			super(size);
			map = new HashMap<>();
			for (int i = 0; i < size; i++) {
				map.put(i, new HashSet<>());
				map.get(i).add(i);
			}
		}

		@Override
		protected void unionTo(int source, int dest) {
			super.unionTo(source, dest);
			map.get(dest).addAll(map.get(source));
		}

		@Override
		public Set<Integer> getSet(int id) {
			return map.get(root(id));
		}
	}

	/**
	 * 配列によるUnionFindの実装
	 * getSetメソッドはO(NlogN)なのでTLEに注意
	 */
	class ArrayUnionFind implements UnionFind {
		int[] parent;
		int[] rank;
		int size;
		public ArrayUnionFind(int size) {
			parent = new int[size];
			for (int i = 0; i < size; i++) {
				parent[i] = i;
			}
			rank = new int[size];
			this.size = size;
		}

		@Override
		public void union(int A, int B) {
			int rootA = root(A);
			int rootB = root(B);
			if (rootA != rootB) {
				if (rank[rootA] < rank[rootB]) {
					unionTo(rootA, rootB);
				} else {
					unionTo(rootB, rootA);
					if (rank[rootA] == rank[rootB]) {
						rank[rootA]++;
					}
				}
			}
		}

		protected void unionTo(int source, int dest) {
			parent[source] = dest;
		}

		@Override
		public boolean judge(int A, int B) {
			return root(A) == root(B);
		}

		@Override
		public Set<Integer> getSet(int id) {
			Set<Integer> set = new HashSet<>();
			IntStream.range(0, size).filter(i -> judge(i, id)).forEach(set::add);
			return set;
		}

		protected int root(int id) {
			if (parent[id] == id) {
				return id;
			}
			parent[id] = root(parent[id]);
			return parent[id];
		}
	}

	/**
	 * 素数のユーティリティ
	 */
	class PrimeNumberUtils {
		boolean[] isPrimeArray;
		List<Integer> primes;

		/**
		 * 素数判定の上限となる値を指定してユーティリティを初期化
		 * @param limit 素数判定の上限(この値以上が素数であるか判定しない)
		 */
		public PrimeNumberUtils(int limit) {
			if (limit > 10000000) {
				System.err.println("上限の値が高すぎるため素数ユーティリティの初期化でTLEする可能性が大変高いです");
			}
			primes = new ArrayList<>();
			isPrimeArray = new boolean[limit];
			if (limit > 2) {
				primes.add(2);
				isPrimeArray[2] = true;
			}

			for (int i = 3; i < limit; i += 2) {
				if (isPrime(i, primes)) {
					primes.add(i);
					isPrimeArray[i] = true;
				}
			}
		}

		public List<Integer> getPrimeNumberList() {
			return primes;
		}

		public boolean isPrime(int n) {
			return isPrimeArray[n];
		}

		private boolean isPrime(int n, List<Integer> primes) {
			for (int prime : primes) {
				if (n % prime == 0) {
					return false;
				}
				if (prime > Math.sqrt(n)) {
					break;
				}
			}
			return true;
		}
	}

	interface BitSet {
		void set(int index, boolean bit);
		boolean get(int index);
		void shiftRight(int num);
		void shiftLeft(int num);
		void or(BitSet bitset);
		void and(BitSet bitset);
	}

	/**
	 * Longの配列によるBitSetの実装
	 * get/setはO(1)
	 * shift/or/andはO(size / 64)
	 */
	class LongBit implements BitSet {
		long[] bitArray;

		public LongBit(int size) {
			bitArray = new long[((size + 63) / 64)];
		}

		@Override
		public void set(int index, boolean bit) {
			int segment = index / 64;
			int inIndex = index % 64;
			if (bit) {
				bitArray[segment] |= 1L << inIndex;
			} else {
				bitArray[segment] &= ~(1L << inIndex);
			}
		}

		@Override
		public boolean get(int index) {
			int segment = index / 64;
			int inIndex = index % 64;
			return (bitArray[segment] & (1L << inIndex)) != 0L;
		}

		@Override
		public void shiftRight(int num) {
			int shiftSeg = num / 64;
			int shiftInI = num % 64;
			for (int segment = 0; segment < bitArray.length; segment++) {
				int sourceSeg = segment + shiftSeg;
				if (sourceSeg < bitArray.length) {
					bitArray[segment] = bitArray[sourceSeg] >>> shiftInI;
					if (shiftInI > 0 && sourceSeg + 1 < bitArray.length) {
						bitArray[segment] |= bitArray[sourceSeg + 1] << (64 - shiftInI);
					}
				} else {
					bitArray[segment] = 0L;
				}
			}
		}

		@Override
		public void shiftLeft(int num) {
			int shiftSeg = num / 64;
			int shiftInI = num % 64;
			for (int segment = bitArray.length - 1; segment >= 0; segment--) {
				int sourceSeg = segment - shiftSeg;
				if (sourceSeg >= 0) {
					bitArray[segment] = bitArray[sourceSeg] << shiftInI;
					if (shiftInI > 0 && sourceSeg > 0) {
						bitArray[segment] |= bitArray[sourceSeg - 1] >>> (64 - shiftInI);
					}
				} else {
					bitArray[segment] = 0L;
				}
			}
		}

		public long getLong(int segment) {
			return bitArray[segment];
		}

		@Override
		public void or(BitSet bitset) {
			if (!(bitset instanceof LongBit)) {
				return;
			}
			for (int segment = 0; segment < bitArray.length; segment++) {
				bitArray[segment] |= ((LongBit)bitset).getLong(segment);
			}
		}

		@Override
		public void and(BitSet bitset) {
			if (!(bitset instanceof LongBit)) {
				return;
			}
			for (int segment = 0; segment < bitArray.length; segment++) {
				bitArray[segment] &= ((LongBit)bitset).getLong(segment);
			}
		}
	}

}


#include<stdio.h>

int main(){
int n,i,ans=0,juge=0;

 scanf("%d",&n);

 char s[n];

 scanf("%s",s);

 for(i=0;i<n;i++){
    	if(s[i]=='.') {
          ans++;
        }
    }
 juge=ans;
 for(i=0;i<n;i++){
    	if(s[i]=='#') {juge++;}
      	else {juge--;}
      	if(juge<ans) {ans=juge;}
    }
  printf("%d",ans);
	return 0;
}


#include <iostream>
#include <algorithm>
#include <cstring>
#include <list>
#include <set>
#include <deque>
#include <queue>
#include <stack>
#include <vector>
#include <map>
#include <chrono>
#include <math.h>
using namespace std;

using lli = long long int;
using Vint = std::vector<int>;
using Vlli = std::vector<lli>;
using Wint = std::vector<Vint>;
using Wlli = std::vector<Vlli>;
using Vbool = std::vector<bool>;
using Wbool = std::vector<Vbool>;
using pii = std::pair<int, int>;
using pll = std::pair<lli, lli>;
template <class T>
using Vec = std::vector<T>;
template <class T>
using Wec = Vec<Vec<T>>;

constexpr int MOD = 1e9 + 7;
constexpr int INFi = 2e9 + 1;
constexpr lli INFl = (lli)(9e18) + 1;
const std::vector<std::pair<int, int>> DXDY = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
constexpr char BR = '\n';

#define DEBUG(x) std::cerr << #x << " = " << x << '\n';
#define FOR(i, a, b) for(int (i) = (a); (i) < (b); ++(i))
#define FOReq(i, a, b) for(int (i) = (a); (i) <= (b); ++(i))
#define rFOR(i, a, b) for(int (i) = (b); (i) >= (a); --(i))
#define FORstep(i, a, b, step) for(int (i) = (a); i < (b); i += (step))
#define REP(i, n) FOR(i, 0, n)
#define rREP(i, n) rFOR(i, 0, (n-1))
#define vREP(ele, vec) for(auto &(ele) : (vec))
#define vREPcopy(ele, vec) for(auto (ele) : (vec))
#define SORT(A) std::sort((A).begin(), (A).end())
#define RSORT(A) std::sort((A).rbegin(), (A).rend())
#define ALL(A) (A).begin(), (A).end()
// 座標圧縮 (for vector) : ソートしてから使うのが一般的 ; SORT(A) => COORDINATE_COMPRESSION(A)
#define COORDINATE_COMPRESSION(A) (A).erase(unique((A).begin(),(A).end()),(A).end())

template <class T> inline int argmin(std::vector<T> vec){return min_element(vec.begin(), vec.end()) - vec.begin();}
template <class T> inline int argmax(std::vector<T> vec){return max_element(vec.begin(), vec.end()) - vec.begin();}
template <class S, class T> inline void chmax(S &a, T b){if(a < b) a = b;}
template <class S, class T> inline void chmin(S &a, T b){if(a > b) a = b;}
template <class T> inline void reverseSORT(Vec<T> &Array){
  std::sort(Array.begin(), Array.end(), std::greater<T>());
}
inline int BitI(int k){return 1 << k;}
inline lli BitL(int k){return 1LL << k;}
inline void putsDouble(double d){printf("%.16lf\n", d);}
template <class T> inline std::string toString(T n){
  if(n == 0) return "0";
  std::string res;
  if(n < 0){n = -n;while(n != 0){res += (char)(n % 10 + '0'); n /= 10;}
  std::reverse(res.begin(), res.end()); return '-' + res;}
  while(n != 0){res += (char)(n % 10 + '0'); n /= 10;} std::reverse(res.begin(), res.end()); return res;
}

namespace MyFunc{
    using LLi = long long int;
    // GCD(a, b) ; a, bの最大公約数を求める関数
    inline LLi gcd(LLi a, LLi b){ while(b != 0){ a %= b; std::swap(a, b);} return a; }
    // LCM(a, b) ; a, bの最小公倍数を求める関数
    inline LLi lcm(LLi a, LLi b){ return (a * b) / MyFunc::gcd(a, b);}
    // 累乗を求める関数
    inline LLi power(LLi a, LLi n){
        LLi res = 1LL, waiting = a;
        while(n != 0LL){ if((n & 1LL) != 0LL) res *= waiting; waiting *= waiting; n >>= 1;}
        return res;
    }
    // 累乗の余りを求める関数
    inline LLi power_mod(LLi a, LLi n, LLi mod_number___ = 1e9 + 7){
        LLi res = 1LL, waiting = a;
        while(n != 0LL){ if((n & 1LL) != 0LL){ res *= waiting; res %= mod_number___;}
            waiting *= waiting; waiting %= mod_number___; n >>= 1; }
        return res;
    }
    // Z/pZ上の逆元を求める関数 (フェルマーの小定理)
    inline LLi inverse_mod(LLi a, LLi mod_number___ = 1e9 + 7){
        return MyFunc::power_mod(a, mod_number___-2);
    }
    inline LLi inverse_mod_euclid(LLi a, LLi mod_number___ = 1e9+7){
        LLi b = mod_number___, u = 1, v = 0;
        while (b != 0) { LLi t = a / b; a -= t * b; std::swap(a, b);
            u -= t * v; std::swap(u, v);}
        u %= mod_number___; if (u < 0) u += mod_number___;
        return u;
    }
    // 素数であるかを判定する関数
    template <typename Integer_type>
    inline bool isPrime(Integer_type n){
        if(n < 2) return false; if(n == 2) return true; if(n % 2 == 0) return false;
        for(Integer_type x = 3; x * x <= n; ++++x) if(n % x == 0) return false;
        return true;
    }
    // 素数であるかの真偽表を返す　: n ≥ 1
    inline std::vector<bool> primeTable(int n){
        std::vector<bool> res(n+1, true); res[0] = false; res[1] = false;
        for(int x = 2; x * x <= n; ++x) if(res[x]){
            for(int i = 2 * x; i <= n; i += x){ res[i] = false; } }
        return std::move(res);
    }
    // 素因数分解したベクトルを返す　; {素因数, 指数}
    template <typename Integer_type>
    inline std::vector<std::pair<Integer_type, int>> prime_factorization(Integer_type n){
        std::vector<std::pair<Integer_type, int>> res(0);
        if(n <= 0) return std::move(res); // 例外処理　: nが 0 以下
        if(n % 2 == 0){
            n /= 2; int cnt = 1; while(n % 2 == 0){ n /= 2; cnt++;}
            res.emplace_back(make_pair(2, cnt));
        }
        Integer_type x = 3;
        while(x * x <= n){
            if(n % x == 0){
                n /= x; int cnt = 1; while(n % x == 0){ n /= x; cnt++; }
                res.emplace_back(make_pair(x, cnt));
            } ++++x;
        } if(n > 1) res.emplace_back(make_pair(n, 1));
        return std::move(res);
    }
}

// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

int main(void){
    int n; scanf("%d", &n);
    char str[n+1];
    scanf("%s", str);
    int white = 0, black = 0;
    REP(i, n){
        if(str[i] == '.') white++;
        else black++;
    }
    int til_white = 0, til_black = 0;
    int res = black;
    REP(i, n){
        // i番目までを白で埋めて, 以降を 全て黒にする
        int diffL = i  - til_white;
        int diffR = (n - i) - (black - til_black);
        if(diffL + diffR < res) res = diffL + diffR;
        if(str[i] == '.') til_white++;
        else til_black++;
    }
    printf("%d\n", res);
    return 0;
}


#include <stdio.h>
#include <algorithm>

const int N = 200005;

char a[N];

int main() {
  int n;
  scanf("%d %s", &n, a);
  int w = 0;
  for (int i = 0; i < n; i++) {
    w += (a[i] == '.');
  }
  int b = 0;
  int ans = (1 << 30);
  for (int i = 0; i < n; i++) {
    ans = std::min(ans, b + w);
    if (a[i] == '#') {
      b++;
    }
    if (a[i] == '.') {
      w--;
    }
  }
  printf("%d\n", std::min(ans, b + w));
  return 0;
}


#include <iostream>
#include<vector>
using namespace std;
int main(void){
    int n;
    string s;
    cin >> n;
    cin >> s;
   vector<int> b(n + 1);
   vector<int> w(n + 1);
   for(int i = 1;i <= n;i++){
         if(s[i - 1] == '#')b[i]++;
         else w[i]++;
         b[i] += b[i - 1];
         w[i] += w[i - 1];
   }
   int ans = n;
   for(int i = 0;i <= n;i++){
         ans = min(ans,i - b[i] + w[n] - w[i]);
   }
   cout << ans << endl;
}


#include <iostream>
using namespace std;
int main(void){
    int n;
    string s;
    cin >> n;
    cin >> s;
    int wht = 0;
    for(int i = 0;i < n;i++){
          if(s[i] == '.')wht++;
    }
    int ans = 0;
    for(int i = 0;i < n;i++){
          if(i < wht){
                if(s[i] != '.')ans++;
          }else{
                if(s[i] != '#')ans++;
          }
    }
    cout << ans << endl;
}


#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); ++i)
using namespace std;
using ll = long long;
using P = pair<int, int>;

int N;

int solve(string S, string T) {
    int res = 0;
    rep(i, N - 1) {
        if (S[i] == T[0] && S[i + 1] == T[1]) {
            S[i + 1] = T[0];
            ++res;
        }
    }
    return res;
}

int main() {
    cin >> N;
    string S;
    cin >> S;

    string rS = S;
    reverse(rS.begin(), rS.end());
    cout << min(solve(S, "#."), solve(rS, ".#")) << endl;
}


#include<stdio.h>
int main(){
  int N,cnt=0,i,min;
  scanf("%d",&N);
  char S[N+1];
  scanf("%s",S);

  for(i=0;i<N;i++){
    if(S[i]=='.')cnt++;
  }
  if(S[0]=='.'){
    cnt--;
    min=cnt;
  }
  else {
    min=cnt;
    cnt++;
  }

  for(i=1;i<N;i++){
    if(S[i]=='.')cnt--;
    else cnt++;
    if(cnt<min){
      min=cnt;
    }
  }
  printf("%d\n",min);

  return 0;
}


#include<stdio.h>
#include<string.h>
#include<math.h>
int main(void) {
	int n,w = 0,b = 0;
	scanf("%d", &n);
	char s[n + 1];
	scanf("%s", s);
	for (int i = 0;i < n;i++) {
		if (s[i] == '.') {
			w++;
		}
	}
	if (w == 0 || w == n) {
		printf("0");
		return 0;
	}
	int ans = w;
	for (int i = 0;i < n;i++) {
		if (s[i] == '.') {
			w--;
		}
		else {
			b++;
		}
		if (ans > w + b) {
			ans = w + b;
		}
	}
	printf("%d", ans);
	return 0;
}


#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>

int max(int a,int b){
	if(a>b)return a;
	return b;
}

int compare_char(char *a,char *b){
	return strcmp(a,b);
}

int intsort(const void *a, const void *b){
	return *(int*)b - *(int*)a;
	/*qsort(a,aの配列数,sizeof(int),intsort);*/
}

int longsort(const void *a, const void *b){
	long *A=(long *)a;
	long *B=(long *)b;
	if(*A>*B) return -1;
	if(*A<*B) return 1;
	return 0;
}

int main(){
  int i=0,N,min,cnt=0;
  char ss[200001];
  scanf("%d",&N);
  scanf("%s",ss);
  while(i<N){
    if(ss[i]=='.'){
      cnt++;
    }
    i++;
  }
  if(ss[0]=='.')cnt--;
  min=cnt;
  for(i=1;i<N;i++){
    if(ss[i]=='.')cnt--;
    if(ss[i-1]=='#')cnt++;
    if(min>cnt)min=cnt;
  }
  printf("%d\n",min);
  return 0;
}


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#define MOD1 1000000007
#define MOD2 998244353
#define LIMIT1 200002
#define LIMIT2 500002
typedef long long ll;
typedef long double ld;
typedef const void cv;
#define rep(i,n) for((i)=0;(i)<(n);(i)++)
#define per(i,n) for((i)=(n)-1;(i)>=0;(i)--)
#define max(a,b) ((a)>(b) ? (a) : (b))
#define min(a,b) ((a)<(b) ? (a) : (b))
#define zt(a,b) (max((a),(b))-min((a),(b)))
ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
ll nPr(int n,int r){ll i,result=1;rep(i,r){result*=(ll)(n-i);}return result;}
ll nCr(int n,int r){ll i,result=1;if(n<r) return 0;rep(i,min(r,n-r)){result*=(ll)(n-i);result/=(ll)(i+1);}return result;}
#define nHr(n,r) nCr((int)((n)+(r)+1),(int)(r))
#define sankaku(x) (((x)*((x)+1))/2)
int dx[8]={1,0,-1,0,1,-1,-1,1},dy[8]={0,1,0,-1,1,1,-1,-1};
int upint(cv *a, cv *b) { return *(int *)a < *(int *)b ? -1 : *(int *)a > *(int *)b ? 1 : 0; }
int downint(cv *a, cv *b) { return *(int *)a < *(int *)b ? 1 : *(int *)a > *(int *)b ? -1 : 0; }
int upchar(cv *left, cv *right) {return strcmp((char *)left,(char *)right);}
int downchar(cv *left, cv *right) {return strcmp((char *)right,(char *)left);}
void tmpInit(int *c,ll m) {ll i;rep(i,m) c[i]=i;}
ll modpow(ll a, ll n, ll mod) {
    ll res = 1;
    while (n > 0) {
        if (n & 1){
            res *= a; if(mod>=1) res %= mod;
        }
        a *= a; if(mod>=1) a %= mod;
        n >>= 1;
    }
    return res;
}
void initialize(){

}
int main(void){
  initialize();
  ll n,m,i,j,k,result=0,tmp=0,tmp2=0;
  int a[LIMIT2]={0};
  char s[LIMIT1];

  scanf("%lld",&n);
  scanf("%s",s);
  result=1<<29;
  rep(i,n){
    tmp2+=((s[i]=='.') ? 1 : 0);
  }
  rep(i,n){
    tmp +=((s[i]=='#') ? 1 : 0);
    tmp2-=((s[i]=='.') ? 1 : 0);
    result=min(result,tmp+tmp2);
  }
  printf("%lld",result);

  return 0;
}


#include<stdio.h>
#include<stdlib.h>
#include<math.h>
#include<string.h>
#include<stdbool.h>
typedef long long ll;
typedef long double ld;
#define rep(i,l,r)for(ll i=(l);i<(r);i++)
#define repp(i,l,r,k)for(ll i=(l);i<(r);i+=(k))
#define rrep(i,l,r)for(ll i=(l);i>=(r);i--)
#define INF (1LL<<60)
#define MOD1 1000000007
#define MOD2 998244353
#define MAX_N (1 << 17)
#define YES printf("Yes\n")
#define NO printf("No\n")
#define PN printf("\n")

void swap(ll *a, ll *b){ll c;c=*b;*b=*a;*a=c;}
ll max2(ll a,ll b){return a>=b?a:b;}
ll min2(ll a,ll b){return a>=b?b:a;}
ll min3(ll a, ll b, ll c){return (a<=b && a<=c) ? a : b<=c ? b : c;}
ll max3(ll a, ll b, ll c){return (a>=b && a>=c) ? a : b>=c ? b : c;}
ll minn(ll n, ll a[n]){ll b=INF;rep(i,0,n) b=min2(b,a[i]);return b;}
ll maxn(ll n, ll a[n]){ll b=-INF;rep(i,0,n) b=max2(b,a[i]);return b;}
ll ABS(ll a){return a>=0?a:(-a);}
ll POW(ll a, ll b){ll c=1;rep(i,0,b) c*=a;return c;}
ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
ll lcm(ll a,ll b){return a/gcd(a,b)*b;}
ll mod(ll n){return n%=MOD1;}
int upll(const void*a, const void*b){return*(ll*)a<*(ll*)b?-1:*(ll*)a>*(ll*)b?1:0;}
int downll(const void*a, const void*b){return*(ll*)a<*(ll*)b?1:*(ll*)a>*(ll*)b?-1:0;}
void sortup(ll*a,int n){qsort(a,n,sizeof(ll),upll);}
void sortdown(ll*a,int n){qsort(a,n,sizeof(ll),downll);}

typedef struct{ ll aa , bb;}fr;
int cmp1( const void *p, const void *q ) { return ((fr*)p) ->aa - ((fr*)q)->aa;}

int main(void){
    char s[200005];
    ll n,ans=0;
    scanf("%lld%s",&n,s);
    ll bw[n],black;
    bw[n-1]=0;
    rrep(i,n-2,0){
        bw[i]=bw[i+1];
        if(s[i+1]=='#') bw[i]++;
    }
    // rep(i,0,n) printf("%lld ",bw[i]);
    black=bw[0];
    if(s[0]=='#') black++;

    if(s[0]=='#'){
        ans=(n-1)-bw[0];
    }else{
        ans=(n-1)-(bw[0]+1);
    }
    rep(i,1,n){
        // ans=min2(ans, (black-b[]) )
        if(s[i]=='.'){
            ans=min2(ans, (black-bw[i])+1+(n-1-i)-bw[i] );
        }else{
            ans=min2(ans, (black-bw[i]-1)+(n-1-i)-bw[i] );
        }
    }
    ans=min2(ans,black);
    printf("%lld\n",ans);
    return 0;
}


#include<stdio.h>
#include<stdlib.h>
#include<math.h>
#include<string.h>
#include<stdbool.h>
typedef long long ll;
typedef long double ld;
#define rep(i,l,r)for(ll i=(l);i<(r);i++)
#define repp(i,l,r,k)for(ll i=(l);i<(r);i+=(k))
#define rrep(i,l,r)for(ll i=(l);i>=(r);i--)
#define INF (1LL<<60)
#define MOD1 1000000007
#define MOD2 998244353
#define MAX_N (1 << 17)
#define YES printf("Yes\n")
#define NO printf("No\n")
#define PN printf("\n")

void swap(ll *a, ll *b){ll c;c=*b;*b=*a;*a=c;}
ll max2(ll a,ll b){return a>=b?a:b;}
ll min2(ll a,ll b){return a>=b?b:a;}
ll min3(ll a, ll b, ll c){return (a<=b && a<=c) ? a : b<=c ? b : c;}
ll max3(ll a, ll b, ll c){return (a>=b && a>=c) ? a : b>=c ? b : c;}
ll minn(ll n, ll a[n]){ll b=INF;rep(i,0,n) b=min2(b,a[i]);return b;}
ll maxn(ll n, ll a[n]){ll b=-INF;rep(i,0,n) b=max2(b,a[i]);return b;}
ll ABS(ll a){return a>=0?a:(-a);}
ll POW(ll a, ll b){ll c=1;rep(i,0,b) c*=a;return c;}
ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
ll lcm(ll a,ll b){return a/gcd(a,b)*b;}
ll mod(ll n){return n%=MOD1;}
int upll(const void*a, const void*b){return*(ll*)a<*(ll*)b?-1:*(ll*)a>*(ll*)b?1:0;}
int downll(const void*a, const void*b){return*(ll*)a<*(ll*)b?1:*(ll*)a>*(ll*)b?-1:0;}
void sortup(ll*a,int n){qsort(a,n,sizeof(ll),upll);}
void sortdown(ll*a,int n){qsort(a,n,sizeof(ll),downll);}

typedef struct{ ll aa , bb;}fr;
int cmp1( const void *p, const void *q ) { return ((fr*)p) ->aa - ((fr*)q)->aa;}

int main(void){
    char s[200005];
    ll n,ans=0;
    scanf("%lld%s",&n,s);
    ll bw[n],black;
    bw[n-1]=0;
    rrep(i,n-2,0){
        bw[i]=bw[i+1];
        if(s[i+1]=='#') bw[i]++;
    }
    // rep(i,0,n) printf("%lld ",bw[i]);
    black=bw[0];
    if(s[0]=='#') black++;

    if(s[0]=='#'){
        ans=(n-1)-bw[0];
    }else{
        ans=(n-1)-(bw[0]+1);
    }
    rep(i,1,n){
        // ans=min2(ans, (black-b[]) )
        if(s[i]=='.'){
            ans=min2(ans, (black-bw[i])+1+(n-1-i)-bw[i] );
        }else{
            ans=min2(ans, (black-bw[i])+(n-1-i)-bw[i] );
        }
    }
    ans=min2(ans,black);
    printf("%lld\n",ans);
    return 0;
}


module.exports=function(e){var r={};function t(n){if(r[n])return r[n].exports;var o=r[n]={i:n,l:!1,exports:{}};return e[n].call(o.exports,o,o.exports,t),o.l=!0,o.exports}return t.m=e,t.c=r,t.d=function(e,r,n){t.o(e,r)||Object.defineProperty(e,r,{enumerable:!0,get:n})},t.r=function(e){"undefined"!=typeof Symbol&&Symbol.toStringTag&&Object.defineProperty(e,Symbol.toStringTag,{value:"Module"}),Object.defineProperty(e,"__esModule",{value:!0})},t.t=function(e,r){if(1&r&&(e=t(e)),8&r)return e;if(4&r&&"object"==typeof e&&e&&e.__esModule)return e;var n=Object.create(null);if(t.r(n),Object.defineProperty(n,"default",{enumerable:!0,value:e}),2&r&&"string"!=typeof e)for(var o in e)t.d(n,o,function(r){return e[r]}.bind(null,o));return n},t.n=function(e){var r=e&&e.__esModule?function(){return e.default}:function(){return e};return t.d(r,"a",r),r},t.o=function(e,r){return Object.prototype.hasOwnProperty.call(e,r)},t.p="",t(t.s=0)}([function(e,r,t){t(1)(t(2).readFileSync("/dev/stdin","UTF-8"))},function(e,r){e.exports=function(e){for(var r=e.split("\n"),t=Number(r[0]),n=r[1].split(""),o=0,u=0;u<t;u++){"."==n[u]&&(o+=1)}for(var i=o,f=0,l=9999999,c=0;c<t;c++){var a=n[c];"."==a&&(i-=1);var p=f+i;p<l&&(l=p),"#"==a&&(f+=1)}console.log(l)}},function(e,r){e.exports=require("fs")}]);


function Main(input) {
  // 数字
  var N = parseInt(input[0], 10);
  var S = input[1];

  // 0番目から探索するためrightWには全ての白を初期値として入れる
  var leftB = 0;
  var rightW = S.split('.').length - 1;

  var result = rightW;

  for (var i = 0; i < S.length; i++) {
    if (S.charAt(i) === '.') {
      rightW--;
    } else {
      leftB++;
    }
    result = (rightW + leftB) < result ? (rightW + leftB) : result;
  }

  console.log(result);
}

Main(require("fs").readFileSync("/dev/stdin", "utf8").trim().split(/\n|\s/));


const BKRT = "\n";
const SPAC = " ";
const NOSP = "";

function Main(input){
	input = [].concat(...input.split(BKRT).map(a=>a.split(SPAC)));
  const strShift = ()=>input.shift();
  const intShift = ()=>~~input.shift();

  var A = intShift();
  var B = strShift();

  var s = 0;

  for(var i = 0; i < A; i++){
  	if(B[i] == ".")s++;
  }
  var min = s;
  for(var i = 0; i < A; i++){
  	if(B[i] == "."){
    	s--;
    }else{
    	s++;
    }
    min = Math.min(min,s);
  }

  return ~~min;
}

// If you are interested in the algorithms I used,
// there is no need to read down from this line.

((b,c,d)=>"undefined"!=typeof require?console.log(Main(require("fs").readFileSync("/dev/stdin","utf8"))):[b=b.split("\n").slice(1,-1).join("\n"),c=function(){try{return Main(b)}catch(f){return f.stack||f.message}}(),d=typeof c,"string"==d||(c=JSON.stringify(c)),$("<form>").append([[10,b],0,[1,d],0,[10,c]].map(f=>$(f?"<textarea>":"<br>",f&&{rows:f[0],cols:40,text:f[1]}))).appendTo("body")])(`
5
#.##.
`);


var read = require('readline').createInterface({
  input: process.stdin,
  output: process.stdout
});
var obj;
var inLine = [];
read.on('line', function(input){inLine.push(input);});
read.on('close', function(){
  obj = init(inLine);
  myerr("-----start-----");
  var start = new Date();
  Main();
  var end = new Date() - start;
  myerr("----- end -----");
  myerr("time : " + (end) + "ms");
});
function nextInt(){return myconv(next(),1);} function nextStrArray(){return myconv(next(),2);}
function nextIntArray(){return myconv(next(),4);} function nextCharArray(){return myconv(next(),6);}
function next(){return obj.next();} function hasNext(){return obj.hasNext();}
function init(input){
  var returnObj = {
    list : input, index : 0, max : input.length,
    hasNext : function(){return (this.index < this.max);},
    next : function(){if(!this.hasNext()){throw "ArrayIndexOutOfBoundsException これ以上ないよ";}else{var returnInput = this.list[this.index];this.index++;return returnInput;}}
  };
  return returnObj;
}
function myout(s){console.log(s);}
function myerr(s){console.error("debug:" + require("util").inspect(s,false,null));}
//[no]要素の扱い。数値型
//不明値、異常時:引数そのまま返す 1:数値へ変換
//2:半角SPで分割 4:半角SPで分割し、数値配列へ
//6:1文字で分割  7:1文字で分割し、数値配列へ
//8:半角SPで結合 9:改行で結合 0:文字なしで結合
function myconv(i,no){try{switch(no){case 1:return parseInt(i);case 2:return i.split(" ");case 4:return i.split(" ").map(Number);case 6:return i.split("");case 7:return i.split("").map(Number);case 8:return i.join(" ");case 9:return i.join("\n");case 0:return i.join("");default:return i;}}catch(e){return i;}}
function Main(){
	var N = nextInt();
	if(N == 1){
		myout(0);
		return;
	}
	var s = next();
	var siro = new Array(N).fill(0);
	var kuro = new Array(N).fill(0);
	var output = 10000000;
	for(var i = 0; i < N; i++){
		if(s[i] == "#"){
			kuro[i]++;
		}else{
			siro[i]++;
		}
	}
	for(var i = 1; i < N; i++){
		siro[i] += siro[i - 1];
		kuro[i] += kuro[i - 1];
	}
	var siroMax = siro[N - 1];
	if(siroMax == N || siroMax == 0){
		myout(0);
		return;
	}
	if(s[0] == "#"){
		output = siroMax;
	}
	for(var i = 1; i < N; i++){
		if(s[i - 1] == "." && s[i] == "#"){
			output = Math.min(output, kuro[i - 1] + (siroMax - siro[i - 1]));
		}
	}
	myout(output);

}


var read = require('readline').createInterface({
  input: process.stdin,
  output: process.stdout
});
var obj;
var inLine = [];
read.on('line', function(input){inLine.push(input);});
read.on('close', function(){
  obj = init(inLine);
  myerr("-----start-----");
  var start = new Date();
  Main();
  var end = new Date() - start;
  myerr("----- end -----");
  myerr("time : " + (end) + "ms");
});
function nextInt(){return myconv(next(),1);} function nextStrArray(){return myconv(next(),2);}
function nextIntArray(){return myconv(next(),4);} function nextCharArray(){return myconv(next(),6);}
function next(){return obj.next();} function hasNext(){return obj.hasNext();}
function init(input){
  var returnObj = {
    list : input, index : 0, max : input.length,
    hasNext : function(){return (this.index < this.max);},
    next : function(){if(!this.hasNext()){throw "ArrayIndexOutOfBoundsException これ以上ないよ";}else{var returnInput = this.list[this.index];this.index++;return returnInput;}}
  };
  return returnObj;
}
function myout(s){console.log(s);}
function myerr(s){console.error("debug:" + require("util").inspect(s,false,null));}
//[no]要素の扱い。数値型
//不明値、異常時:引数そのまま返す 1:数値へ変換
//2:半角SPで分割 4:半角SPで分割し、数値配列へ
//6:1文字で分割  7:1文字で分割し、数値配列へ
//8:半角SPで結合 9:改行で結合 0:文字なしで結合
function myconv(i,no){try{switch(no){case 1:return parseInt(i);case 2:return i.split(" ");case 4:return i.split(" ").map(Number);case 6:return i.split("");case 7:return i.split("").map(Number);case 8:return i.join(" ");case 9:return i.join("\n");case 0:return i.join("");default:return i;}}catch(e){return i;}}
function Main(){
	var N = nextInt();
	var s = nextCharArray();
	while(s.length > 0 && s[s.length - 1] == "#"){
		s.pop();
	}
	while(s.length > 0 && s[0] == "."){
		s.shift();
	}
	var kuro = 0;
	var siro = 0;
	for(var i = 0; i < s.length; i++){
		if(s[i] == "#"){
			kuro++;
		}else{
			siro++;
		}
	}
	myout(Math.min(siro,kuro));
}


inp = require('fs').readFileSync('/dev/stdin', 'utf8').trim().split('\n')
N = inp.shift() * 1
s = inp.shift()
l = 0
r = s.length
while(s[l] == '.') {
    l++
}
while(s[r-1] == '#') {
    r--
}
c=0
for (i=l; i<r; i++) {
    if (s[i] == '#') {
        c++
    }
}
console.log(Math.min(c, r - l - c))


package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

var sc = bufio.NewScanner(os.Stdin)

func ini() {
	var buf = make([]byte, 10000)
	sc.Buffer(buf, 1000000)
}

func nextLine() string {
	sc.Scan()
	return sc.Text()
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

func main() {
	ini()
	N, _ := strconv.Atoi(nextLine())
	S := nextLine()
	b := make([]int, N+1)

	for i, s := range S {
		if s == '#' {
			b[i+1] = b[i] + 1
		} else {
			b[i+1] = b[i]
		}
	}
	ans := N
	for i := 1; i < N+1; i++ {
		ans = min(ans, b[i]+N-i-b[N]+b[i-1])
	}
	fmt.Println(ans)
}


package main

import (
	"bufio"
	"fmt"
	"os"
)

var sc = bufio.NewScanner(os.Stdin)

func ri() (n int) {
	sc.Scan()
	for _, v := range sc.Bytes() {
		n = n*10 + int(v-48)
	}
	return
}

func rb() []byte {
	sc.Scan()
	return sc.Bytes()
}

func smaller(a, b int) int {
	if a < b {
		return a
	}
	return b
}

func main() {
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1e6), 1e6)
	n, s := ri(), rb()

	ctHash := 0
	for _, ss := range s {
		if ss == '#' {
			ctHash++
		}
	}
	ctDot := n - ctHash

	minCost := smaller(ctHash, ctDot)
	ctHash = 0
	for _, ss := range s {
		switch ss {
		case '#':
			ctHash++
		case '.':
			ctDot--
		}
		if cost := ctHash + ctDot; cost < minCost {
			minCost = cost
		}
	}
	fmt.Println(minCost)
}


package main

import (
	"bufio"
	"fmt"
	"math"
	"os"
	"strconv"
)

var sc = bufio.NewScanner(os.Stdin)
var out = bufio.NewWriter(os.Stdout)

func main() {
	/*/TODO:!!!!!!!テスト用!!!!!!!!!
	sc = bufio.NewScanner(strings.NewReader(`
										`))
	//TODO:!!!!!!!テスト用!!!!!!!!!*/

	buf := make([]byte, 1024*1024)
	sc.Buffer(buf, bufio.MaxScanTokenSize)
	sc.Split(bufio.ScanWords)
	defer out.Flush() // !!!!caution!!!! you must use Fprint(out, ) not Print()
	/* --- code --- */
	//fmt.Fprintln(out, "[DEBUG]", time.Now())

	n := nextInt()
	s := next()

	ans := n
	w := 0
	b := 0
	cw := true

	for i := 0; i < n; i++ {
		if s[i] == '.' {
			w++
		}
	}

	if w == 0 {
		fmt.Fprintln(out, 0)
		return
	}

	for i := 0; i < n; i++ {
		if (cw && s[i] == '#') || ((!cw) && s[i] == '.') {
			if cw {
				ans = minInt(ans, b+w)
			}
			cw = !cw
		}

		if s[i] == '#' {
			b++
		} else {
			w--
		}
	}

	ans = minInt(ans, b+w)

	//99999

	//fmt.Fprintln(out, "[DEBUG]", a)
	fmt.Fprintln(out, ans)
}

//------------------------------------------------------------------------------

// -*-*-*-*-*-*-*-*-
// * I/O utilities *
// -*-*-*-*-*-*-*-*-

func next() string {
	sc.Scan()
	return sc.Text()
}

func nextInt() int {
	a, _ := strconv.Atoi(next())
	return a
}

func nextFloat64() float64 {
	a, _ := strconv.ParseFloat(next(), 64)
	return a
}

func nextInts(n int) []int {
	ret := make([]int, n)
	for i := 0; i < n; i++ {
		ret[i] = nextInt()
	}
	return ret
}
func nextFloats(n int) []float64 {
	ret := make([]float64, n)
	for i := 0; i < n; i++ {
		ret[i] = nextFloat64()
	}
	return ret
}
func nextStrings(n int) []string {
	ret := make([]string, n)
	for i := 0; i < n; i++ {
		ret[i] = next()
	}
	return ret
}

func chars(s string) []string {
	ret := make([]string, len([]rune(s)))
	for i, v := range []rune(s) {
		ret[i] = string(v)
	}
	return ret
}

func absInt(x int) int {
	return int(math.Abs(float64(x)))
}
func minInt(x, y int) int {
	if x < y {
		return x
	}
	return y
}
func maxInt(x, y int) int {
	if x > y {
		return x
	}
	return y
}
func log10(x int) float64 {
	return math.Log10(float64(x))
}


package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

var (
	finv, inv, fac [MAX]int
)

func COM(n, k int) int {
	MOD := int(MOD)
	if n < k {
		return 0
	}
	if n < 0 || k < 0 {
		return 0
	}
	return fac[n] * (finv[k] * finv[n-k] % MOD) % MOD
}

func init() {
	MOD := int(MOD)
	fac[0] = 1
	fac[1] = 1
	finv[0] = 1
	finv[1] = 1
	inv[1] = 1
	for i := 2; i < MAX; i++ {
		fac[i] = fac[i-1] * i % MOD
		inv[i] = MOD - inv[MOD%i]*(MOD/i)%MOD
		finv[i] = finv[i-1] * inv[i] % MOD
	}
	//sc.Split(bufio.ScanLines)
	sc.Split(bufio.ScanWords)
	sc.Buffer([]byte{}, 500100)
}

const (
	MAX = 510000
)

var MOD int64 = 1000000007

func ModAdd(a, b int64) int64 {
	return (a + b) % MOD
}

func ModMul(a, b int64) int64 {
	ans := a * b % MOD
	if ans < 0 {
		ans += MOD
	}
	return ans
}

func ModSub(a, b int64) int64 {
	r := (a%MOD - b%MOD) % MOD
	if r < 0 {
		r += MOD
	}
	return r
}

func ModDiv(a, b int64) int64 {
	return a % MOD * ModInv(b) % MOD
}

func ModPow(a, n int64) int64 {
	var r int64 = 1
	for n > 0 {
		if n&1 == 1 {
			r = r * a % MOD
		}
		a = a * a % MOD
		n >>= 1
	}
	return r
}

func ModInv(a int64) int64 {
	var b, u, v int64 = MOD, 1, 0
	for b > 0 {
		t := a / b
		a -= t * b
		a, b = b, a
		u -= t * v
		u, v = v, u
	}
	u %= MOD
	if u < 0 {
		u += MOD
	}
	return u
}

type Q struct {
	value int
	index int
	K     int
}

type QS []*Q

func (p QS) Len() int           { return len(p) }
func (p QS) Less(i, j int) bool { return p[i].value > p[j].value }
func (pq QS) Swap(i, j int) {
	pq[i], pq[j] = pq[j], pq[i]
	pq[i].index = i
	pq[j].index = j
}

func (pq *QS) Push(x interface{}) {
	n := len(*pq)
	item := x.(*Q)
	item.index = n
	*pq = append(*pq, item)
}

func (pq *QS) Pop() interface{} {
	old := *pq
	n := len(old)
	item := old[n-1]
	old[n-1] = nil  // avoid memory leak
	item.index = -1 // for safety
	*pq = old[0 : n-1]
	return item
}

func GCD(a, b int64) int64 {
	if b == 0 {
		return a
	}
	return GCD(b, a%b)
}

func LCM(a, b int64) int64 {
	return a * b / GCD(a, b)
}

type UnionFind struct {
	par  []int
	size []int
}

func NewUnionFind(size int) *UnionFind {
	return new(UnionFind).init(size)
}

func (uf *UnionFind) init(size int) *UnionFind {
	uf.par = make([]int, size)
	uf.size = make([]int, size)

	for i := 0; i < size; i++ {
		uf.par[i] = i
		uf.size[i] = 1
	}
	return uf
}

func (uf *UnionFind) Unite(p int, q int) {
	rp := uf.Root(p)
	rq := uf.Root(q)
	if rp == rq {
		return
	}
	if uf.size[rp] < uf.size[rq] {
		uf.par[rp] = uf.par[rq]
		uf.size[rq] += uf.size[rp]
	} else {
		uf.par[rq] = uf.par[rp]
		uf.size[rp] += uf.size[rq]
	}
}

func (uf *UnionFind) Root(p int) int {
	for uf.par[p] == p {
		return p
	}
	uf.par[p] = uf.Root(uf.par[p])
	return uf.par[p]
}

func (uf *UnionFind) Size(p int) int {
	return uf.size[uf.Root(p)]
}

func (uf *UnionFind) Same(p int, q int) bool {
	return uf.Root(p) == uf.Root(q)
}

var sc = bufio.NewScanner(os.Stdin)

func getInt() int {
	n, _ := strconv.Atoi(getStr())
	return n
}

func getStr() string {
	sc.Scan()
	return sc.Text()
}

func factor(result map[int]int, num, pnum int) map[int]int {
	if pnum*pnum > num {
		if num != 1 {
			result[num] += 1
		}
		return result
	}

	if num%pnum == 0 {
		num /= pnum
		result[pnum]++
	} else {
		pnum++
	}
	return factor(result, num, pnum)
}

func main() {
	N, S := getInt(), []rune(getStr())

	pos := 0
	ans := 0
	for pos < N {
		if string(S[pos]) == "." {
			pos++
			continue
		}
		var b, w int
		b++
		r := pos + 1
		for r < N {
			s := string(S[r])
			if s == "#" {
				if w > 0 {
					break
				}
				b++
				r++
				continue
			}
			w++
			r++
		}
		add := b
		if b > w {
			add = w
		}
		ans += add
		pos = r
	}
	// #.###.#.#.##..#
	// ##..

	fmt.Println(ans)
}

type IntHeap []int

func (h IntHeap) Len() int           { return len(h) }
func (h IntHeap) Less(i, j int) bool { return h[i] > h[j] }
func (h IntHeap) Swap(i, j int)      { h[i], h[j] = h[j], h[i] }

func (h *IntHeap) Push(x interface{}) {
	// Push and Pop use pointer receivers because they modify the slice's length,
	// not just its contents.
	*h = append(*h, x.(int))
}

func (h *IntHeap) Pop() interface{} {
	old := *h
	n := len(old)
	x := old[n-1]
	*h = old[0 : n-1]
	return x
}

func Reverse(s string) string {
	runes := []rune(s)
	for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
		runes[i], runes[j] = runes[j], runes[i]
	}
	return string(runes)
}


package main

import (
	"bufio"
	"fmt"
	"math"
	"os"
	"reflect"
	"sort"
	"strconv"
	"strings"
	// "regexp"
)

/* sort */
type pair struct {
	index  int64
	p1, p2 interface{}
}
type pairs []pair

func (slice pairs) Len() int {
	return len(slice)
}

func (slice pairs) Less(i, j int) bool {
	return slice[i].index < slice[j].index
}

func (slice pairs) Swap(i, j int) {
	slice[i], slice[j] = slice[j], slice[i]
}

/* sort */
type Int64Slice []int64

func (slice Int64Slice) Len() int {
	return len(slice)
}

func (slice Int64Slice) Less(i, j int) bool {
	return slice[i] < slice[j]
}

func (slice Int64Slice) Swap(i, j int) {
	slice[i], slice[j] = slice[j], slice[i]
}
func Int64s(a []int64)                    { sort.Sort(Int64Slice(a)) }
func Int64sSliceAreSorted(a []int64) bool { return sort.IsSorted(Int64Slice(a)) }

const (
	initialBufSize = 1e4
	maxBufSize     = 1e8
	INF            = 1e8
)

var (
	scanner = bufio.NewScanner(os.Stdin)
	writer  = bufio.NewWriter(os.Stdout)
	di      = []int64{-1, 0, 1, 0}
	dj      = []int64{0, -1, 0, 1}
	di8     = []int64{-1, -1, 0, 1, 1, 1, 0, -1}
	dj8     = []int64{0, -1, -1, -1, 0, 1, 1, 1}
)

func main() {
	buf := make([]byte, initialBufSize)
	scanner.Buffer(buf, maxBufSize)
	scanner.Split(bufio.ScanWords)
	N := readInt()
	S := readStrings()
	var lstart int64
	var rstart = N - 1
	for lstart < rstart {
		if S[lstart] == "#" && S[rstart] == "." {
			break
		}
		if S[lstart] != "#" {
			lstart++
		}
		if S[rstart] != "." {
			rstart--
		}
	}
	var ans int64
	for i := rstart; i > lstart; i-- {
		if S[i] == "." {
			ans++
		}
	}
	fmt.Println(ans)
}

/*==========================================
 *             Library
 *==========================================*/
func NextPermutation(x sort.Interface) bool {
	n := x.Len() - 1
	if n < 1 {
		return false
	}
	j := n - 1
	for ; !x.Less(j, j+1); j-- {
		if j == 0 {
			return false
		}
	}
	l := n
	for !x.Less(j, l) {
		l--
	}
	x.Swap(j, l)
	for k, l := j+1, n; k < l; {
		x.Swap(k, l)
		k++
		l--
	}
	return true
}
func doubleAry(h int64, w int64, init int64) (res [][]int64) {
	res = make([][]int64, h)
	for i := int64(0); i < h; i++ {
		res[i] = make([]int64, w)
		for j := int64(0); j < w; j++ {
			res[i][j] = init
		}
	}
	return
}

func aryEq(a []int64, b []int64) bool {
	return reflect.DeepEqual(a, b)
}

func clone(n []int64) (r []int64) {
	r = make([]int64, len(n))
	for i := 0; i < len(n); i++ {
		r[i] = n[i]
	}
	return
}
func write(s string) {
	writer.WriteString(s)
}

func print() {
	writer.Flush()
}

// scanner.Split(bufio.ScanWords) をコメントアウトしないと使用不可
func readLine() (s string) {
	if scanner.Scan() {
		s = scanner.Text()
	}
	return s
}

func readInt() (read int64) {
	scanner.Scan()
	read, err := strconv.ParseInt(scanner.Text(), 10, 64)
	if err != nil {
		panic(err)
	}
	return
}

func readFloat() (read float64) {
	scanner.Scan()
	read, err := strconv.ParseFloat(scanner.Text(), 64)
	if err != nil {
		panic(err)
	}
	return
}

func readRunes() (read []rune) {
	scanner.Scan()
	for _, v := range scanner.Text() {
		read = append(read, v)
	}
	return
}

func readString() (read string) {
	scanner.Scan()
	read = scanner.Text()
	return
}

func readStrings() (read []string) {
	scanner.Scan()
	for _, v := range scanner.Text() {
		read = append(read, string(v))
	}
	return
}

func s2i(s string) int64 {
	var intVal, e = strconv.ParseInt(s, 10, 64)
	if e != nil {
		panic(e)
	}
	return intVal
}

func i2s(i int64) string {
	var strVal = strconv.FormatInt(i, 10)
	return strVal
}

func s2f(s string) float64 {
	var floatVal, e = strconv.ParseFloat(s, 64)
	if e != nil {
		panic(e)
	}
	return floatVal
}

func abs(i int64) int64 {
	return int64(math.Abs(float64(i)))
}

func max(a ...int64) int64 {
	ans := int64(0)
	for i, v := range a {
		if i == 0 {
			ans = v
		}
		if ans < v {
			ans = v
		}
	}
	return ans
}
func min(a ...int64) int64 {
	ans := int64(0)
	for i, v := range a {
		if i == 0 {
			ans = v
		}
		if ans > v {
			ans = v
		}
	}
	return ans
}

func sum(i []int64) int64 {
	sum := int64(0)
	for _, val := range i {
		sum += val
	}
	return sum
}

func split(s string) []string {
	return strings.Fields(s)
}

func strAry2intAry(strs []string) []int64 {
	var ret = make([]int64, 0, len(strs))
	for _, str := range strs {
		var intVal = s2i(str)
		ret = append(ret, intVal)
	}
	return ret
}

func intAry2strAry(nums []int64) []string {
	var ret = make([]string, 0, len(nums))
	for _, num := range nums {
		var strVal = i2s(num)
		ret = append(ret, strVal)
	}
	return ret
}

func ary2str(strs []string) string {
	return strings.Join(strs, " ")
}

func reverse(res []int64) []int64 {
	for i, j := 0, len(res)-1; i < j; i, j = i+1, j-1 {
		res[i], res[j] = res[j], res[i]
	}
	return res
}
func reverseStr(res []string) []string {
	for i, j := 0, len(res)-1; i < j; i, j = i+1, j-1 {
		res[i], res[j] = res[j], res[i]
	}
	return res
}

func ini(res []int, init int) {
	if len(res) == 0 {
		return
	}
	res[0] = init
	for i := 0; i < len(res); i++ {
		copy(res[i:], res[:i])
	}
}

//
// func regexpExample() {
//     // Your code here!
//     var str = "13:20"
//     r := regexp.MustCompile(`(\d+):(\d+)`)
//     fmt.Println(r.FindStringSubmatch(str))
// }

// type Country struct {
//     gold int
//     silver int
//     blonze int
// }

// // 複数ソートのサンプル
// func stableSortExample() []Country{
//     var country = []Country {
//         {gold:1, silver:2, blonze:3},
//         {gold:1, silver:2, blonze:3},
//         {gold:1, silver:3, blonze:2},
//         {gold:1, silver:3, blonze:3},
//     }
//     sort.SliceStable(country, func(i, j int) bool { return country[i].blonze > country[j].blonze })
//     sort.SliceStable(country, func(i, j int) bool { return country[i].silver > country[j].silver })
//     sort.SliceStable(country, func(i, j int) bool { return country[i].gold > country[j].gold })
//     return country
// }


package main

import (
	"bufio"
	"fmt"
	"math"
	"os"
	"strconv"
)

var sc = bufio.NewScanner(os.Stdin)
var out = bufio.NewWriter(os.Stdout)

func main() {
	/*/TODO:!!!!!!!テスト用!!!!!!!!!
	sc = bufio.NewScanner(strings.NewReader(`
									`))
	//TODO:!!!!!!!テスト用!!!!!!!!!*/

	buf := make([]byte, 1024*1024)
	sc.Buffer(buf, bufio.MaxScanTokenSize)
	sc.Split(bufio.ScanWords)
	defer out.Flush() // !!!!caution!!!! you must use Fprint(out, ) not Print()
	/* --- code --- */
	//fmt.Fprintln(out, "[DEBUG]", time.Now())

	n := nextInt()
	s := next()

	ans := n
	w := 0
	b := 0
	cw := s[0] == '.'

	for i := 0; i < n; i++ {
		if s[i] == '.' {
			w++
		}
	}

	if w == 0 {
		fmt.Fprintln(out, 0)
		return
	}

	for i := 0; i < n; i++ {
		if (cw && s[i] == '#') || ((!cw) && s[i] == '.') {
			if cw {
				ans = minInt(ans, b+w)
			}
			cw = !cw
		}

		if s[i] == '#' {
			b++
		} else {
			w--
		}
	}

	ans = minInt(ans, b+w)

	//fmt.Fprintln(out, "[DEBUG]", a)
	fmt.Fprintln(out, ans)
}

//------------------------------------------------------------------------------

// -*-*-*-*-*-*-*-*-
// * I/O utilities *
// -*-*-*-*-*-*-*-*-

func next() string {
	sc.Scan()
	return sc.Text()
}

func nextInt() int {
	a, _ := strconv.Atoi(next())
	return a
}

func nextFloat64() float64 {
	a, _ := strconv.ParseFloat(next(), 64)
	return a
}

func nextInts(n int) []int {
	ret := make([]int, n)
	for i := 0; i < n; i++ {
		ret[i] = nextInt()
	}
	return ret
}
func nextFloats(n int) []float64 {
	ret := make([]float64, n)
	for i := 0; i < n; i++ {
		ret[i] = nextFloat64()
	}
	return ret
}
func nextStrings(n int) []string {
	ret := make([]string, n)
	for i := 0; i < n; i++ {
		ret[i] = next()
	}
	return ret
}

func chars(s string) []string {
	ret := make([]string, len([]rune(s)))
	for i, v := range []rune(s) {
		ret[i] = string(v)
	}
	return ret
}

func absInt(x int) int {
	return int(math.Abs(float64(x)))
}
func minInt(x, y int) int {
	if x < y {
		return x
	}
	return y
}
func maxInt(x, y int) int {
	if x > y {
		return x
	}
	return y
}
func log10(x int) float64 {
	return math.Log10(float64(x))
}


n = gets.chomp.to_i
s = gets.chomp
countb = 0
countw = 0
abs = 0
pos = n - 1

while pos >= 0
  if s[pos] == '.' then
    break
  end
  pos -= 1
end

while pos >= 0
  if s[pos] == '.' then
    countw += 1
  else
    countb += 1
  end

  if countw < countb then
    abs += countw
    countb = 0
    countw = 0
  end
  pos -= 1
end

puts abs + [countw, countb].min


n = gets.chomp.to_i
s = gets.chomp

pos = n - 1
while pos >= 0
  if s[pos] == '#'
    pos -= 1
    next
  end
  break
end

black_cnt = 0
white_cnt = 0
ans = 0
while pos >= 0
  if s[pos] == '#'
    black_cnt += 1
  else
    white_cnt += 1
  end
  if black_cnt > white_cnt
    ans += white_cnt
    black_cnt = 0
    white_cnt = 0
  end
  pos -= 1
end
puts ans + [black_cnt, white_cnt].min


n = gets.chomp.to_i
s = gets.chomp
countb = 0
countw = 0
countm = 0
abs = 0
pos = n - 1

while pos >= 0
  if s[pos] == '.' then
    break
  end
  pos -= 1
end

while pos >= 0
  if s[pos] == '.' then
    countm += 1
    countw += 1
  else
    countb += 1
  end

  if countm < countb then
    abs += countw
    countb = 0
    countw = 0
    countm = 0
  end
  pos -= 1
end

puts abs + [countw, countb].min


n = gets.to_i
s = gets.chomp
j = n - 2

res = 0
while j >= 0
  if s[j] == "#" && s[j + 1] == "."
    res += 1
  end
  j -= 1
end
puts res


n = gets.to_i
s = gets.chomp
i = 0
j = n - 1

res = 0
while i < j
  while s[i] == "." && i < j
    i += 1
  end
  while s[j] == "#" && i < j
    j -= 1
  end

  if i < j && s[i] == "#"
    res += 1
    i += 1
  end
  if i < j && s[j] == "."
    res += 1
    j -= 1
  end
end
puts res


n = gets.to_i
s = gets.chomp
blacks = s.split(".").map { |c| c.size }.reject { |n| n.zero? }
whites = s.split("#").map { |c| c.size }.reject { |n| n.zero? }
min_black_change = blacks.inject(0) { |res, num| res + num }
min_black_change -= blacks[-1] if min_black_change > 0 && s[-1] == "#"
min_white_change = whites.inject(0) { |res, num| res + num }
min_white_change -= whites[0] if min_white_change > 0 && s[0] == "."
puts [min_black_change, min_white_change].min


macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};

    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };

    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };

    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };

    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };

    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}
use std::cmp;
fn main() {
    input! {
        n: usize,
        s: chars,
    }
    let mut black_cnt = 0;
    let mut white_cnt = 0;
    for c in &s {
        if *c == '#' {
            black_cnt += 1;
        } else {
            white_cnt += 1;
        }
    }
    let mut fwd_b = 0;
    let mut bwd_w = white_cnt;
    let mut ans = cmp::min(black_cnt, white_cnt);

    for c in &s {
        if *c == '#' {
            fwd_b += 1;
        } else {
            bwd_w -= 1;
        }
        ans = cmp::min(ans, fwd_b + bwd_w);
    }
    println!("{}", ans);
 }


#[allow(unused_macros)]
macro_rules! p {
    ($x:expr $(, $tail:expr)*) => {
        let mut s = String::new();
        s.push_str(format!("{:?}", $x).as_str());
        $(
            s.push_str(format!(", {:?}", $tail).as_str());
        )*
        println!("{}", s);
    };
}

#[allow(unused_macros)]
macro_rules! pl {
    ($($x:expr), *) => {
        $(println!("{:?}", $x);)*
    };
}

macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

macro_rules! stdin {
    () => {{
        use std::io::Read;
        let mut s = String::new();
        std::io::stdin().read_to_string(&mut s).unwrap();
        s
    }};
}

macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};

    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };

    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };

    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };

    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };

    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}

fn main() {
    println!("{}", solve(stdin!()));
}

fn solve(src: String) -> String {
    input! {
        source = src,
        n: usize,
        s: chars,
    }
    let mut white = 0;
    for i in 0..n {
        if s[i] == '.' {
            white += 1;
        }
    }
    let mut left_black = 0;
    let mut right_white = white;
    let mut ans = right_white;
    for i in 0..n {
        if s[i] == '#' {
            left_black += 1;
        } else if s[i] == '.' {
            right_white -= 1;
        }
        ans = std::cmp::min(ans, left_black + right_white);
    }
    ans.to_string()
}

// Test Code

macro_rules! test {
    ($($input:expr => $output:expr),* $(,)*) => {
        #[test]
        fn solve_test() {
            $(
                assert_eq!(solve($input.to_string()), $output);
            )*
        }
    };
}

test! {
r"
3
#.#
" => "1",

r"
5
#.##.
" => "2",

r"
9
.........
" => "0",

r"
9
##...#.#.
" => "4",
}


#[allow(unused_imports)]
use std::cmp::{Ordering};

#[allow(unused_imports)]
use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, VecDeque};

#[allow(unused_imports)]
use std::io::{stdin, stdout, BufWriter, Write};

#[allow(unused_imports)]
use std::iter::FromIterator;

#[allow(unused_macros)]
macro_rules! min {
    ($x: expr) => ($x);
    ($x: expr, $($z: expr),+) => {{
        std::cmp::min($x, min!($($z),*))
    }}
}

#[allow(unused_macros)]
macro_rules! max {
    ($x: expr) => ($x);
    ($x: expr, $($z: expr),+) => {{
        std::cmp::max($x, max!($($z),*))
    }}
}

#[allow(unused_macros)]
macro_rules! get {
    ([$t: ty]) => {
        {
            let mut line = String::new();
            stdin().read_line(&mut line).unwrap();
            line.split_whitespace().map(|t|t.parse::<$t>().unwrap()).collect::<Vec<_>>()
        }
    };
    ([$t: ty];$n: expr) => {
        (0..$n).map(|_|get!([$t])).collect::<Vec<_>>()
    };
    ($t: ty) => {
        {
            let mut line = String::new();
            stdin().read_line(&mut line).unwrap();
            line.trim().parse::<$t>().unwrap()
        }
    };
    ($($t: ty),*) => {
        {
            let mut line = String::new();
            stdin().read_line(&mut line).unwrap();
            let mut iter = line.split_whitespace();
            ($(iter.next().unwrap().parse::<$t>().unwrap(),)*)
        }
    };
    ($t: ty; $n: expr) => {
        (0..$n).map(|_|get!($t)).collect::<Vec<_>>()
    };
    ($($t: ty),*; $n: expr) => {
        (0..$n).map(|_|get!($($t),*)).collect::<Vec<_>>()
    };
}

#[allow(unused_macros)]
macro_rules! debug {
    ($($a:expr),*) => {
        #[cfg(debug_assertions)]
        writeln!(&mut std::io::stderr(), concat!("[DEBUG] ", $(stringify!($a), "={:?} "),*), $($a),*).unwrap();
    }
}

const BIG_STACK_SIZE: bool = true;

#[allow(dead_code)]
fn main() {
    use std::thread;
    if BIG_STACK_SIZE {
        thread::Builder::new()
            .stack_size(32 * 1024 * 1024)
            .name("solve".into())
            .spawn(solve)
            .unwrap()
            .join()
            .unwrap();
    } else {
        solve();
    }
}

fn solve() {
    let n = get!(usize);
    let s = get!(String).chars().collect::<Vec<_>>();

    let mut whites = vec![0; n+1];
    for i in 0..n {
        whites[i+1] = if s[i] == '.' {
            whites[i] + 1
        } else {
            whites[i]
        };
    }

    let  mut mn = std::usize::MAX;
    for i in 0..(n+1) {
        mn = min!(mn, (i-whites[i]) + (whites[n]-whites[i]));
    }
    println!("{}", mn);
}