var bigInt=function(undefined){"use strict";var BASE=1e7,LOG_BASE=7,MAX_INT=9007199254740992,MAX_INT_ARR=smallToArray(MAX_INT),DEFAULT_ALPHABET="0123456789abcdefghijklmnopqrstuvwxyz";var supportsNativeBigInt=typeof BigInt==="function";function Integer(v,radix,alphabet,caseSensitive){if(typeof v==="undefined")return Integer[0];if(typeof radix!=="undefined")return+radix===10&&!alphabet?parseValue(v):parseBase(v,radix,alphabet,caseSensitive);return parseValue(v)}function BigInteger(value,sign){this.value=value;this.sign=sign;this.isSmall=false}BigInteger.prototype=Object.create(Integer.prototype);function SmallInteger(value){this.value=value;this.sign=value<0;this.isSmall=true}SmallInteger.prototype=Object.create(Integer.prototype);function NativeBigInt(value){this.value=value}NativeBigInt.prototype=Object.create(Integer.prototype);function isPrecise(n){return-MAX_INT<n&&n<MAX_INT}function smallToArray(n){if(n<1e7)return[n];if(n<1e14)return[n%1e7,Math.floor(n/1e7)];return[n%1e7,Math.floor(n/1e7)%1e7,Math.floor(n/1e14)]}function arrayToSmall(arr){trim(arr);var length=arr.length;if(length<4&&compareAbs(arr,MAX_INT_ARR)<0){switch(length){case 0:return 0;case 1:return arr[0];case 2:return arr[0]+arr[1]*BASE;default:return arr[0]+(arr[1]+arr[2]*BASE)*BASE}}return arr}function trim(v){var i=v.length;while(v[--i]===0);v.length=i+1}function createArray(length){var x=new Array(length);var i=-1;while(++i<length){x[i]=0}return x}function truncate(n){if(n>0)return Math.floor(n);return Math.ceil(n)}function add(a,b){var l_a=a.length,l_b=b.length,r=new Array(l_a),carry=0,base=BASE,sum,i;for(i=0;i<l_b;i++){sum=a[i]+b[i]+carry;carry=sum>=base?1:0;r[i]=sum-carry*base}while(i<l_a){sum=a[i]+carry;carry=sum===base?1:0;r[i++]=sum-carry*base}if(carry>0)r.push(carry);return r}function addAny(a,b){if(a.length>=b.length)return add(a,b);return add(b,a)}function addSmall(a,carry){var l=a.length,r=new Array(l),base=BASE,sum,i;for(i=0;i<l;i++){sum=a[i]-base+carry;carry=Math.floor(sum/base);r[i]=sum-carry*base;carry+=1}while(carry>0){r[i++]=carry%base;carry=Math.floor(carry/base)}return r}BigInteger.prototype.add=function(v){var n=parseValue(v);if(this.sign!==n.sign){return this.subtract(n.negate())}var a=this.value,b=n.value;if(n.isSmall){return new BigInteger(addSmall(a,Math.abs(b)),this.sign)}return new BigInteger(addAny(a,b),this.sign)};BigInteger.prototype.plus=BigInteger.prototype.add;SmallInteger.prototype.add=function(v){var n=parseValue(v);var a=this.value;if(a<0!==n.sign){return this.subtract(n.negate())}var b=n.value;if(n.isSmall){if(isPrecise(a+b))return new SmallInteger(a+b);b=smallToArray(Math.abs(b))}return new BigInteger(addSmall(b,Math.abs(a)),a<0)};SmallInteger.prototype.plus=SmallInteger.prototype.add;NativeBigInt.prototype.add=function(v){return new NativeBigInt(this.value+parseValue(v).value)};NativeBigInt.prototype.plus=NativeBigInt.prototype.add;function subtract(a,b){var a_l=a.length,b_l=b.length,r=new Array(a_l),borrow=0,base=BASE,i,difference;for(i=0;i<b_l;i++){difference=a[i]-borrow-b[i];if(difference<0){difference+=base;borrow=1}else borrow=0;r[i]=difference}for(i=b_l;i<a_l;i++){difference=a[i]-borrow;if(difference<0)difference+=base;else{r[i++]=difference;break}r[i]=difference}for(;i<a_l;i++){r[i]=a[i]}trim(r);return r}function subtractAny(a,b,sign){var value;if(compareAbs(a,b)>=0){value=subtract(a,b)}else{value=subtract(b,a);sign=!sign}value=arrayToSmall(value);if(typeof value==="number"){if(sign)value=-value;return new SmallInteger(value)}return new BigInteger(value,sign)}function subtractSmall(a,b,sign){var l=a.length,r=new Array(l),carry=-b,base=BASE,i,difference;for(i=0;i<l;i++){difference=a[i]+carry;carry=Math.floor(difference/base);difference%=base;r[i]=difference<0?difference+base:difference}r=arrayToSmall(r);if(typeof r==="number"){if(sign)r=-r;return new SmallInteger(r)}return new BigInteger(r,sign)}BigInteger.prototype.subtract=function(v){var n=parseValue(v);if(this.sign!==n.sign){return this.add(n.negate())}var a=this.value,b=n.value;if(n.isSmall)return subtractSmall(a,Math.abs(b),this.sign);return subtractAny(a,b,this.sign)};BigInteger.prototype.minus=BigInteger.prototype.subtract;SmallInteger.prototype.subtract=function(v){var n=parseValue(v);var a=this.value;if(a<0!==n.sign){return this.add(n.negate())}var b=n.value;if(n.isSmall){return new SmallInteger(a-b)}return subtractSmall(b,Math.abs(a),a>=0)};SmallInteger.prototype.minus=SmallInteger.prototype.subtract;NativeBigInt.prototype.subtract=function(v){return new NativeBigInt(this.value-parseValue(v).value)};NativeBigInt.prototype.minus=NativeBigInt.prototype.subtract;BigInteger.prototype.negate=function(){return new BigInteger(this.value,!this.sign)};SmallInteger.prototype.negate=function(){var sign=this.sign;var small=new SmallInteger(-this.value);small.sign=!sign;return small};NativeBigInt.prototype.negate=function(){return new NativeBigInt(-this.value)};BigInteger.prototype.abs=function(){return new BigInteger(this.value,false)};SmallInteger.prototype.abs=function(){return new SmallInteger(Math.abs(this.value))};NativeBigInt.prototype.abs=function(){return new NativeBigInt(this.value>=0?this.value:-this.value)};function multiplyLong(a,b){var a_l=a.length,b_l=b.length,l=a_l+b_l,r=createArray(l),base=BASE,product,carry,i,a_i,b_j;for(i=0;i<a_l;++i){a_i=a[i];for(var j=0;j<b_l;++j){b_j=b[j];product=a_i*b_j+r[i+j];carry=Math.floor(product/base);r[i+j]=product-carry*base;r[i+j+1]+=carry}}trim(r);return r}function multiplySmall(a,b){var l=a.length,r=new Array(l),base=BASE,carry=0,product,i;for(i=0;i<l;i++){product=a[i]*b+carry;carry=Math.floor(product/base);r[i]=product-carry*base}while(carry>0){r[i++]=carry%base;carry=Math.floor(carry/base)}return r}function shiftLeft(x,n){var r=[];while(n-- >0)r.push(0);return r.concat(x)}function multiplyKaratsuba(x,y){var n=Math.max(x.length,y.length);if(n<=30)return multiplyLong(x,y);n=Math.ceil(n/2);var b=x.slice(n),a=x.slice(0,n),d=y.slice(n),c=y.slice(0,n);var ac=multiplyKaratsuba(a,c),bd=multiplyKaratsuba(b,d),abcd=multiplyKaratsuba(addAny(a,b),addAny(c,d));var product=addAny(addAny(ac,shiftLeft(subtract(subtract(abcd,ac),bd),n)),shiftLeft(bd,2*n));trim(product);return product}function useKaratsuba(l1,l2){return-.012*l1-.012*l2+15e-6*l1*l2>0}BigInteger.prototype.multiply=function(v){var n=parseValue(v),a=this.value,b=n.value,sign=this.sign!==n.sign,abs;if(n.isSmall){if(b===0)return Integer[0];if(b===1)return this;if(b===-1)return this.negate();abs=Math.abs(b);if(abs<BASE){return new BigInteger(multiplySmall(a,abs),sign)}b=smallToArray(abs)}if(useKaratsuba(a.length,b.length))return new BigInteger(multiplyKaratsuba(a,b),sign);return new BigInteger(multiplyLong(a,b),sign)};BigInteger.prototype.times=BigInteger.prototype.multiply;function multiplySmallAndArray(a,b,sign){if(a<BASE){return new BigInteger(multiplySmall(b,a),sign)}return new BigInteger(multiplyLong(b,smallToArray(a)),sign)}SmallInteger.prototype._multiplyBySmall=function(a){if(isPrecise(a.value*this.value)){return new SmallInteger(a.value*this.value)}return multiplySmallAndArray(Math.abs(a.value),smallToArray(Math.abs(this.value)),this.sign!==a.sign)};BigInteger.prototype._multiplyBySmall=function(a){if(a.value===0)return Integer[0];if(a.value===1)return this;if(a.value===-1)return this.negate();return multiplySmallAndArray(Math.abs(a.value),this.value,this.sign!==a.sign)};SmallInteger.prototype.multiply=function(v){return parseValue(v)._multiplyBySmall(this)};SmallInteger.prototype.times=SmallInteger.prototype.multiply;NativeBigInt.prototype.multiply=function(v){return new NativeBigInt(this.value*parseValue(v).value)};NativeBigInt.prototype.times=NativeBigInt.prototype.multiply;function square(a){var l=a.length,r=createArray(l+l),base=BASE,product,carry,i,a_i,a_j;for(i=0;i<l;i++){a_i=a[i];carry=0-a_i*a_i;for(var j=i;j<l;j++){a_j=a[j];product=2*(a_i*a_j)+r[i+j]+carry;carry=Math.floor(product/base);r[i+j]=product-carry*base}r[i+l]=carry}trim(r);return r}BigInteger.prototype.square=function(){return new BigInteger(square(this.value),false)};SmallInteger.prototype.square=function(){var value=this.value*this.value;if(isPrecise(value))return new SmallInteger(value);return new BigInteger(square(smallToArray(Math.abs(this.value))),false)};NativeBigInt.prototype.square=function(v){return new NativeBigInt(this.value*this.value)};function divMod1(a,b){var a_l=a.length,b_l=b.length,base=BASE,result=createArray(b.length),divisorMostSignificantDigit=b[b_l-1],lambda=Math.ceil(base/(2*divisorMostSignificantDigit)),remainder=multiplySmall(a,lambda),divisor=multiplySmall(b,lambda),quotientDigit,shift,carry,borrow,i,l,q;if(remainder.length<=a_l)remainder.push(0);divisor.push(0);divisorMostSignificantDigit=divisor[b_l-1];for(shift=a_l-b_l;shift>=0;shift--){quotientDigit=base-1;if(remainder[shift+b_l]!==divisorMostSignificantDigit){quotientDigit=Math.floor((remainder[shift+b_l]*base+remainder[shift+b_l-1])/divisorMostSignificantDigit)}carry=0;borrow=0;l=divisor.length;for(i=0;i<l;i++){carry+=quotientDigit*divisor[i];q=Math.floor(carry/base);borrow+=remainder[shift+i]-(carry-q*base);carry=q;if(borrow<0){remainder[shift+i]=borrow+base;borrow=-1}else{remainder[shift+i]=borrow;borrow=0}}while(borrow!==0){quotientDigit-=1;carry=0;for(i=0;i<l;i++){carry+=remainder[shift+i]-base+divisor[i];if(carry<0){remainder[shift+i]=carry+base;carry=0}else{remainder[shift+i]=carry;carry=1}}borrow+=carry}result[shift]=quotientDigit}remainder=divModSmall(remainder,lambda)[0];return[arrayToSmall(result),arrayToSmall(remainder)]}function divMod2(a,b){var a_l=a.length,b_l=b.length,result=[],part=[],base=BASE,guess,xlen,highx,highy,check;while(a_l){part.unshift(a[--a_l]);trim(part);if(compareAbs(part,b)<0){result.push(0);continue}xlen=part.length;highx=part[xlen-1]*base+part[xlen-2];highy=b[b_l-1]*base+b[b_l-2];if(xlen>b_l){highx=(highx+1)*base}guess=Math.ceil(highx/highy);do{check=multiplySmall(b,guess);if(compareAbs(check,part)<=0)break;guess--}while(guess);result.push(guess);part=subtract(part,check)}result.reverse();return[arrayToSmall(result),arrayToSmall(part)]}function divModSmall(value,lambda){var length=value.length,quotient=createArray(length),base=BASE,i,q,remainder,divisor;remainder=0;for(i=length-1;i>=0;--i){divisor=remainder*base+value[i];q=truncate(divisor/lambda);remainder=divisor-q*lambda;quotient[i]=q|0}return[quotient,remainder|0]}function divModAny(self,v){var value,n=parseValue(v);if(supportsNativeBigInt){return[new NativeBigInt(self.value/n.value),new NativeBigInt(self.value%n.value)]}var a=self.value,b=n.value;var quotient;if(b===0)throw new Error("Cannot divide by zero");if(self.isSmall){if(n.isSmall){return[new SmallInteger(truncate(a/b)),new SmallInteger(a%b)]}return[Integer[0],self]}if(n.isSmall){if(b===1)return[self,Integer[0]];if(b==-1)return[self.negate(),Integer[0]];var abs=Math.abs(b);if(abs<BASE){value=divModSmall(a,abs);quotient=arrayToSmall(value[0]);var remainder=value[1];if(self.sign)remainder=-remainder;if(typeof quotient==="number"){if(self.sign!==n.sign)quotient=-quotient;return[new SmallInteger(quotient),new SmallInteger(remainder)]}return[new BigInteger(quotient,self.sign!==n.sign),new SmallInteger(remainder)]}b=smallToArray(abs)}var comparison=compareAbs(a,b);if(comparison===-1)return[Integer[0],self];if(comparison===0)return[Integer[self.sign===n.sign?1:-1],Integer[0]];if(a.length+b.length<=200)value=divMod1(a,b);else value=divMod2(a,b);quotient=value[0];var qSign=self.sign!==n.sign,mod=value[1],mSign=self.sign;if(typeof quotient==="number"){if(qSign)quotient=-quotient;quotient=new SmallInteger(quotient)}else quotient=new BigInteger(quotient,qSign);if(typeof mod==="number"){if(mSign)mod=-mod;mod=new SmallInteger(mod)}else mod=new BigInteger(mod,mSign);return[quotient,mod]}BigInteger.prototype.divmod=function(v){var result=divModAny(this,v);return{quotient:result[0],remainder:result[1]}};NativeBigInt.prototype.divmod=SmallInteger.prototype.divmod=BigInteger.prototype.divmod;BigInteger.prototype.divide=function(v){return divModAny(this,v)[0]};NativeBigInt.prototype.over=NativeBigInt.prototype.divide=function(v){return new NativeBigInt(this.value/parseValue(v).value)};SmallInteger.prototype.over=SmallInteger.prototype.divide=BigInteger.prototype.over=BigInteger.prototype.divide;BigInteger.prototype.mod=function(v){return divModAny(this,v)[1]};NativeBigInt.prototype.mod=NativeBigInt.prototype.remainder=function(v){return new NativeBigInt(this.value%parseValue(v).value)};SmallInteger.prototype.remainder=SmallInteger.prototype.mod=BigInteger.prototype.remainder=BigInteger.prototype.mod;BigInteger.prototype.pow=function(v){var n=parseValue(v),a=this.value,b=n.value,value,x,y;if(b===0)return Integer[1];if(a===0)return Integer[0];if(a===1)return Integer[1];if(a===-1)return n.isEven()?Integer[1]:Integer[-1];if(n.sign){return Integer[0]}if(!n.isSmall)throw new Error("The exponent "+n.toString()+" is too large.");if(this.isSmall){if(isPrecise(value=Math.pow(a,b)))return new SmallInteger(truncate(value))}x=this;y=Integer[1];while(true){if(b&1===1){y=y.times(x);--b}if(b===0)break;b/=2;x=x.square()}return y};SmallInteger.prototype.pow=BigInteger.prototype.pow;NativeBigInt.prototype.pow=function(v){var n=parseValue(v);var a=this.value,b=n.value;var _0=BigInt(0),_1=BigInt(1),_2=BigInt(2);if(b===_0)return Integer[1];if(a===_0)return Integer[0];if(a===_1)return Integer[1];if(a===BigInt(-1))return n.isEven()?Integer[1]:Integer[-1];if(n.isNegative())return new NativeBigInt(_0);var x=this;var y=Integer[1];while(true){if((b&_1)===_1){y=y.times(x);--b}if(b===_0)break;b/=_2;x=x.square()}return y};BigInteger.prototype.modPow=function(exp,mod){exp=parseValue(exp);mod=parseValue(mod);if(mod.isZero())throw new Error("Cannot take modPow with modulus 0");var r=Integer[1],base=this.mod(mod);while(exp.isPositive()){if(base.isZero())return Integer[0];if(exp.isOdd())r=r.multiply(base).mod(mod);exp=exp.divide(2);base=base.square().mod(mod)}return r};NativeBigInt.prototype.modPow=SmallInteger.prototype.modPow=BigInteger.prototype.modPow;function compareAbs(a,b){if(a.length!==b.length){return a.length>b.length?1:-1}for(var i=a.length-1;i>=0;i--){if(a[i]!==b[i])return a[i]>b[i]?1:-1}return 0}BigInteger.prototype.compareAbs=function(v){var n=parseValue(v),a=this.value,b=n.value;if(n.isSmall)return 1;return compareAbs(a,b)};SmallInteger.prototype.compareAbs=function(v){var n=parseValue(v),a=Math.abs(this.value),b=n.value;if(n.isSmall){b=Math.abs(b);return a===b?0:a>b?1:-1}return-1};NativeBigInt.prototype.compareAbs=function(v){var a=this.value;var b=parseValue(v).value;a=a>=0?a:-a;b=b>=0?b:-b;return a===b?0:a>b?1:-1};BigInteger.prototype.compare=function(v){if(v===Infinity){return-1}if(v===-Infinity){return 1}var n=parseValue(v),a=this.value,b=n.value;if(this.sign!==n.sign){return n.sign?1:-1}if(n.isSmall){return this.sign?-1:1}return compareAbs(a,b)*(this.sign?-1:1)};BigInteger.prototype.compareTo=BigInteger.prototype.compare;SmallInteger.prototype.compare=function(v){if(v===Infinity){return-1}if(v===-Infinity){return 1}var n=parseValue(v),a=this.value,b=n.value;if(n.isSmall){return a==b?0:a>b?1:-1}if(a<0!==n.sign){return a<0?-1:1}return a<0?1:-1};SmallInteger.prototype.compareTo=SmallInteger.prototype.compare;NativeBigInt.prototype.compare=function(v){if(v===Infinity){return-1}if(v===-Infinity){return 1}var a=this.value;var b=parseValue(v).value;return a===b?0:a>b?1:-1};NativeBigInt.prototype.compareTo=NativeBigInt.prototype.compare;BigInteger.prototype.equals=function(v){return this.compare(v)===0};NativeBigInt.prototype.eq=NativeBigInt.prototype.equals=SmallInteger.prototype.eq=SmallInteger.prototype.equals=BigInteger.prototype.eq=BigInteger.prototype.equals;BigInteger.prototype.notEquals=function(v){return this.compare(v)!==0};NativeBigInt.prototype.neq=NativeBigInt.prototype.notEquals=SmallInteger.prototype.neq=SmallInteger.prototype.notEquals=BigInteger.prototype.neq=BigInteger.prototype.notEquals;BigInteger.prototype.greater=function(v){return this.compare(v)>0};NativeBigInt.prototype.gt=NativeBigInt.prototype.greater=SmallInteger.prototype.gt=SmallInteger.prototype.greater=BigInteger.prototype.gt=BigInteger.prototype.greater;BigInteger.prototype.lesser=function(v){return this.compare(v)<0};NativeBigInt.prototype.lt=NativeBigInt.prototype.lesser=SmallInteger.prototype.lt=SmallInteger.prototype.lesser=BigInteger.prototype.lt=BigInteger.prototype.lesser;BigInteger.prototype.greaterOrEquals=function(v){return this.compare(v)>=0};NativeBigInt.prototype.geq=NativeBigInt.prototype.greaterOrEquals=SmallInteger.prototype.geq=SmallInteger.prototype.greaterOrEquals=BigInteger.prototype.geq=BigInteger.prototype.greaterOrEquals;BigInteger.prototype.lesserOrEquals=function(v){return this.compare(v)<=0};NativeBigInt.prototype.leq=NativeBigInt.prototype.lesserOrEquals=SmallInteger.prototype.leq=SmallInteger.prototype.lesserOrEquals=BigInteger.prototype.leq=BigInteger.prototype.lesserOrEquals;BigInteger.prototype.isEven=function(){return(this.value[0]&1)===0};SmallInteger.prototype.isEven=function(){return(this.value&1)===0};NativeBigInt.prototype.isEven=function(){return(this.value&BigInt(1))===BigInt(0)};BigInteger.prototype.isOdd=function(){return(this.value[0]&1)===1};SmallInteger.prototype.isOdd=function(){return(this.value&1)===1};NativeBigInt.prototype.isOdd=function(){return(this.value&BigInt(1))===BigInt(1)};BigInteger.prototype.isPositive=function(){return!this.sign};SmallInteger.prototype.isPositive=function(){return this.value>0};NativeBigInt.prototype.isPositive=SmallInteger.prototype.isPositive;BigInteger.prototype.isNegative=function(){return this.sign};SmallInteger.prototype.isNegative=function(){return this.value<0};NativeBigInt.prototype.isNegative=SmallInteger.prototype.isNegative;BigInteger.prototype.isUnit=function(){return false};SmallInteger.prototype.isUnit=function(){return Math.abs(this.value)===1};NativeBigInt.prototype.isUnit=function(){return this.abs().value===BigInt(1)};BigInteger.prototype.isZero=function(){return false};SmallInteger.prototype.isZero=function(){return this.value===0};NativeBigInt.prototype.isZero=function(){return this.value===BigInt(0)};BigInteger.prototype.isDivisibleBy=function(v){var n=parseValue(v);if(n.isZero())return false;if(n.isUnit())return true;if(n.compareAbs(2)===0)return this.isEven();return this.mod(n).isZero()};NativeBigInt.prototype.isDivisibleBy=SmallInteger.prototype.isDivisibleBy=BigInteger.prototype.isDivisibleBy;function isBasicPrime(v){var n=v.abs();if(n.isUnit())return false;if(n.equals(2)||n.equals(3)||n.equals(5))return true;if(n.isEven()||n.isDivisibleBy(3)||n.isDivisibleBy(5))return false;if(n.lesser(49))return true}function millerRabinTest(n,a){var nPrev=n.prev(),b=nPrev,r=0,d,t,i,x;while(b.isEven())b=b.divide(2),r++;next:for(i=0;i<a.length;i++){if(n.lesser(a[i]))continue;x=bigInt(a[i]).modPow(b,n);if(x.isUnit()||x.equals(nPrev))continue;for(d=r-1;d!=0;d--){x=x.square().mod(n);if(x.isUnit())return false;if(x.equals(nPrev))continue next}return false}return true}BigInteger.prototype.isPrime=function(strict){var isPrime=isBasicPrime(this);if(isPrime!==undefined)return isPrime;var n=this.abs();var bits=n.bitLength();if(bits<=64)return millerRabinTest(n,[2,3,5,7,11,13,17,19,23,29,31,37]);var logN=Math.log(2)*bits.toJSNumber();var t=Math.ceil(strict===true?2*Math.pow(logN,2):logN);for(var a=[],i=0;i<t;i++){a.push(bigInt(i+2))}return millerRabinTest(n,a)};NativeBigInt.prototype.isPrime=SmallInteger.prototype.isPrime=BigInteger.prototype.isPrime;BigInteger.prototype.isProbablePrime=function(iterations){var isPrime=isBasicPrime(this);if(isPrime!==undefined)return isPrime;var n=this.abs();var t=iterations===undefined?5:iterations;for(var a=[],i=0;i<t;i++){a.push(bigInt.randBetween(2,n.minus(2)))}return millerRabinTest(n,a)};NativeBigInt.prototype.isProbablePrime=SmallInteger.prototype.isProbablePrime=BigInteger.prototype.isProbablePrime;BigInteger.prototype.modInv=function(n){var t=bigInt.zero,newT=bigInt.one,r=parseValue(n),newR=this.abs(),q,lastT,lastR;while(!newR.isZero()){q=r.divide(newR);lastT=t;lastR=r;t=newT;r=newR;newT=lastT.subtract(q.multiply(newT));newR=lastR.subtract(q.multiply(newR))}if(!r.isUnit())throw new Error(this.toString()+" and "+n.toString()+" are not co-prime");if(t.compare(0)===-1){t=t.add(n)}if(this.isNegative()){return t.negate()}return t};NativeBigInt.prototype.modInv=SmallInteger.prototype.modInv=BigInteger.prototype.modInv;BigInteger.prototype.next=function(){var value=this.value;if(this.sign){return subtractSmall(value,1,this.sign)}return new BigInteger(addSmall(value,1),this.sign)};SmallInteger.prototype.next=function(){var value=this.value;if(value+1<MAX_INT)return new SmallInteger(value+1);return new BigInteger(MAX_INT_ARR,false)};NativeBigInt.prototype.next=function(){return new NativeBigInt(this.value+BigInt(1))};BigInteger.prototype.prev=function(){var value=this.value;if(this.sign){return new BigInteger(addSmall(value,1),true)}return subtractSmall(value,1,this.sign)};SmallInteger.prototype.prev=function(){var value=this.value;if(value-1>-MAX_INT)return new SmallInteger(value-1);return new BigInteger(MAX_INT_ARR,true)};NativeBigInt.prototype.prev=function(){return new NativeBigInt(this.value-BigInt(1))};var powersOfTwo=[1];while(2*powersOfTwo[powersOfTwo.length-1]<=BASE)powersOfTwo.push(2*powersOfTwo[powersOfTwo.length-1]);var powers2Length=powersOfTwo.length,highestPower2=powersOfTwo[powers2Length-1];function shift_isSmall(n){return Math.abs(n)<=BASE}BigInteger.prototype.shiftLeft=function(v){var n=parseValue(v).toJSNumber();if(!shift_isSmall(n)){throw new Error(String(n)+" is too large for shifting.")}if(n<0)return this.shiftRight(-n);var result=this;if(result.isZero())return result;while(n>=powers2Length){result=result.multiply(highestPower2);n-=powers2Length-1}return result.multiply(powersOfTwo[n])};NativeBigInt.prototype.shiftLeft=SmallInteger.prototype.shiftLeft=BigInteger.prototype.shiftLeft;BigInteger.prototype.shiftRight=function(v){var remQuo;var n=parseValue(v).toJSNumber();if(!shift_isSmall(n)){throw new Error(String(n)+" is too large for shifting.")}if(n<0)return this.shiftLeft(-n);var result=this;while(n>=powers2Length){if(result.isZero()||result.isNegative()&&result.isUnit())return result;remQuo=divModAny(result,highestPower2);result=remQuo[1].isNegative()?remQuo[0].prev():remQuo[0];n-=powers2Length-1}remQuo=divModAny(result,powersOfTwo[n]);return remQuo[1].isNegative()?remQuo[0].prev():remQuo[0]};NativeBigInt.prototype.shiftRight=SmallInteger.prototype.shiftRight=BigInteger.prototype.shiftRight;function bitwise(x,y,fn){y=parseValue(y);var xSign=x.isNegative(),ySign=y.isNegative();var xRem=xSign?x.not():x,yRem=ySign?y.not():y;var xDigit=0,yDigit=0;var xDivMod=null,yDivMod=null;var result=[];while(!xRem.isZero()||!yRem.isZero()){xDivMod=divModAny(xRem,highestPower2);xDigit=xDivMod[1].toJSNumber();if(xSign){xDigit=highestPower2-1-xDigit}yDivMod=divModAny(yRem,highestPower2);yDigit=yDivMod[1].toJSNumber();if(ySign){yDigit=highestPower2-1-yDigit}xRem=xDivMod[0];yRem=yDivMod[0];result.push(fn(xDigit,yDigit))}var sum=fn(xSign?1:0,ySign?1:0)!==0?bigInt(-1):bigInt(0);for(var i=result.length-1;i>=0;i-=1){sum=sum.multiply(highestPower2).add(bigInt(result[i]))}return sum}BigInteger.prototype.not=function(){return this.negate().prev()};NativeBigInt.prototype.not=SmallInteger.prototype.not=BigInteger.prototype.not;BigInteger.prototype.and=function(n){return bitwise(this,n,function(a,b){return a&b})};NativeBigInt.prototype.and=SmallInteger.prototype.and=BigInteger.prototype.and;BigInteger.prototype.or=function(n){return bitwise(this,n,function(a,b){return a|b})};NativeBigInt.prototype.or=SmallInteger.prototype.or=BigInteger.prototype.or;BigInteger.prototype.xor=function(n){return bitwise(this,n,function(a,b){return a^b})};NativeBigInt.prototype.xor=SmallInteger.prototype.xor=BigInteger.prototype.xor;var LOBMASK_I=1<<30,LOBMASK_BI=(BASE&-BASE)*(BASE&-BASE)|LOBMASK_I;function roughLOB(n){var v=n.value,x=typeof v==="number"?v|LOBMASK_I:typeof v==="bigint"?v|BigInt(LOBMASK_I):v[0]+v[1]*BASE|LOBMASK_BI;return x&-x}function integerLogarithm(value,base){if(base.compareTo(value)<=0){var tmp=integerLogarithm(value,base.square(base));var p=tmp.p;var e=tmp.e;var t=p.multiply(base);return t.compareTo(value)<=0?{p:t,e:e*2+1}:{p:p,e:e*2}}return{p:bigInt(1),e:0}}BigInteger.prototype.bitLength=function(){var n=this;if(n.compareTo(bigInt(0))<0){n=n.negate().subtract(bigInt(1))}if(n.compareTo(bigInt(0))===0){return bigInt(0)}return bigInt(integerLogarithm(n,bigInt(2)).e).add(bigInt(1))};NativeBigInt.prototype.bitLength=SmallInteger.prototype.bitLength=BigInteger.prototype.bitLength;function max(a,b){a=parseValue(a);b=parseValue(b);return a.greater(b)?a:b}function min(a,b){a=parseValue(a);b=parseValue(b);return a.lesser(b)?a:b}function gcd(a,b){a=parseValue(a).abs();b=parseValue(b).abs();if(a.equals(b))return a;if(a.isZero())return b;if(b.isZero())return a;var c=Integer[1],d,t;while(a.isEven()&&b.isEven()){d=min(roughLOB(a),roughLOB(b));a=a.divide(d);b=b.divide(d);c=c.multiply(d)}while(a.isEven()){a=a.divide(roughLOB(a))}do{while(b.isEven()){b=b.divide(roughLOB(b))}if(a.greater(b)){t=b;b=a;a=t}b=b.subtract(a)}while(!b.isZero());return c.isUnit()?a:a.multiply(c)}function lcm(a,b){a=parseValue(a).abs();b=parseValue(b).abs();return a.divide(gcd(a,b)).multiply(b)}function randBetween(a,b){a=parseValue(a);b=parseValue(b);var low=min(a,b),high=max(a,b);var range=high.subtract(low).add(1);if(range.isSmall)return low.add(Math.floor(Math.random()*range));var digits=toBase(range,BASE).value;var result=[],restricted=true;for(var i=0;i<digits.length;i++){var top=restricted?digits[i]:BASE;var digit=truncate(Math.random()*top);result.push(digit);if(digit<top)restricted=false}return low.add(Integer.fromArray(result,BASE,false))}var parseBase=function(text,base,alphabet,caseSensitive){alphabet=alphabet||DEFAULT_ALPHABET;text=String(text);if(!caseSensitive){text=text.toLowerCase();alphabet=alphabet.toLowerCase()}var length=text.length;var i;var absBase=Math.abs(base);var alphabetValues={};for(i=0;i<alphabet.length;i++){alphabetValues[alphabet[i]]=i}for(i=0;i<length;i++){var c=text[i];if(c==="-")continue;if(c in alphabetValues){if(alphabetValues[c]>=absBase){if(c==="1"&&absBase===1)continue;throw new Error(c+" is not a valid digit in base "+base+".")}}}base=parseValue(base);var digits=[];var isNegative=text[0]==="-";for(i=isNegative?1:0;i<text.length;i++){var c=text[i];if(c in alphabetValues)digits.push(parseValue(alphabetValues[c]));else if(c==="<"){var start=i;do{i++}while(text[i]!==">"&&i<text.length);digits.push(parseValue(text.slice(start+1,i)))}else throw new Error(c+" is not a valid character")}return parseBaseFromArray(digits,base,isNegative)};function parseBaseFromArray(digits,base,isNegative){var val=Integer[0],pow=Integer[1],i;for(i=digits.length-1;i>=0;i--){val=val.add(digits[i].times(pow));pow=pow.times(base)}return isNegative?val.negate():val}function stringify(digit,alphabet){alphabet=alphabet||DEFAULT_ALPHABET;if(digit<alphabet.length){return alphabet[digit]}return"<"+digit+">"}function toBase(n,base){base=bigInt(base);if(base.isZero()){if(n.isZero())return{value:[0],isNegative:false};throw new Error("Cannot convert nonzero numbers to base 0.")}if(base.equals(-1)){if(n.isZero())return{value:[0],isNegative:false};if(n.isNegative())return{value:[].concat.apply([],Array.apply(null,Array(-n.toJSNumber())).map(Array.prototype.valueOf,[1,0])),isNegative:false};var arr=Array.apply(null,Array(n.toJSNumber()-1)).map(Array.prototype.valueOf,[0,1]);arr.unshift([1]);return{value:[].concat.apply([],arr),isNegative:false}}var neg=false;if(n.isNegative()&&base.isPositive()){neg=true;n=n.abs()}if(base.isUnit()){if(n.isZero())return{value:[0],isNegative:false};return{value:Array.apply(null,Array(n.toJSNumber())).map(Number.prototype.valueOf,1),isNegative:neg}}var out=[];var left=n,divmod;while(left.isNegative()||left.compareAbs(base)>=0){divmod=left.divmod(base);left=divmod.quotient;var digit=divmod.remainder;if(digit.isNegative()){digit=base.minus(digit).abs();left=left.next()}out.push(digit.toJSNumber())}out.push(left.toJSNumber());return{value:out.reverse(),isNegative:neg}}function toBaseString(n,base,alphabet){var arr=toBase(n,base);return(arr.isNegative?"-":"")+arr.value.map(function(x){return stringify(x,alphabet)}).join("")}BigInteger.prototype.toArray=function(radix){return toBase(this,radix)};SmallInteger.prototype.toArray=function(radix){return toBase(this,radix)};NativeBigInt.prototype.toArray=function(radix){return toBase(this,radix)};BigInteger.prototype.toString=function(radix,alphabet){if(radix===undefined)radix=10;if(radix!==10)return toBaseString(this,radix,alphabet);var v=this.value,l=v.length,str=String(v[--l]),zeros="0000000",digit;while(--l>=0){digit=String(v[l]);str+=zeros.slice(digit.length)+digit}var sign=this.sign?"-":"";return sign+str};SmallInteger.prototype.toString=function(radix,alphabet){if(radix===undefined)radix=10;if(radix!=10)return toBaseString(this,radix,alphabet);return String(this.value)};NativeBigInt.prototype.toString=SmallInteger.prototype.toString;NativeBigInt.prototype.toJSON=BigInteger.prototype.toJSON=SmallInteger.prototype.toJSON=function(){return this.toString()};BigInteger.prototype.valueOf=function(){return parseInt(this.toString(),10)};BigInteger.prototype.toJSNumber=BigInteger.prototype.valueOf;SmallInteger.prototype.valueOf=function(){return this.value};SmallInteger.prototype.toJSNumber=SmallInteger.prototype.valueOf;NativeBigInt.prototype.valueOf=NativeBigInt.prototype.toJSNumber=function(){return parseInt(this.toString(),10)};function parseStringValue(v){if(isPrecise(+v)){var x=+v;if(x===truncate(x))return supportsNativeBigInt?new NativeBigInt(BigInt(x)):new SmallInteger(x);throw new Error("Invalid integer: "+v)}var sign=v[0]==="-";if(sign)v=v.slice(1);var split=v.split(/e/i);if(split.length>2)throw new Error("Invalid integer: "+split.join("e"));if(split.length===2){var exp=split[1];if(exp[0]==="+")exp=exp.slice(1);exp=+exp;if(exp!==truncate(exp)||!isPrecise(exp))throw new Error("Invalid integer: "+exp+" is not a valid exponent.");var text=split[0];var decimalPlace=text.indexOf(".");if(decimalPlace>=0){exp-=text.length-decimalPlace-1;text=text.slice(0,decimalPlace)+text.slice(decimalPlace+1)}if(exp<0)throw new Error("Cannot include negative exponent part for integers");text+=new Array(exp+1).join("0");v=text}var isValid=/^([0-9][0-9]*)$/.test(v);if(!isValid)throw new Error("Invalid integer: "+v);if(supportsNativeBigInt){return new NativeBigInt(BigInt(sign?"-"+v:v))}var r=[],max=v.length,l=LOG_BASE,min=max-l;while(max>0){r.push(+v.slice(min,max));min-=l;if(min<0)min=0;max-=l}trim(r);return new BigInteger(r,sign)}function parseNumberValue(v){if(supportsNativeBigInt){return new NativeBigInt(BigInt(v))}if(isPrecise(v)){if(v!==truncate(v))throw new Error(v+" is not an integer.");return new SmallInteger(v)}return parseStringValue(v.toString())}function parseValue(v){if(typeof v==="number"){return parseNumberValue(v)}if(typeof v==="string"){return parseStringValue(v)}if(typeof v==="bigint"){return new NativeBigInt(v)}return v}for(var i=0;i<1e3;i++){Integer[i]=parseValue(i);if(i>0)Integer[-i]=parseValue(-i)}Integer.one=Integer[1];Integer.zero=Integer[0];Integer.minusOne=Integer[-1];Integer.max=max;Integer.min=min;Integer.gcd=gcd;Integer.lcm=lcm;Integer.isInstance=function(x){return x instanceof BigInteger||x instanceof SmallInteger||x instanceof NativeBigInt};Integer.randBetween=randBetween;Integer.fromArray=function(digits,base,isNegative){return parseBaseFromArray(digits.map(parseValue),parseValue(base||10),isNegative)};return Integer}();if(typeof module!=="undefined"&&module.hasOwnProperty("exports")){module.exports=bigInt}if(typeof define==="function"&&define.amd){define("big-integer",[],function(){return bigInt})}

function main(input) {
  const lines = input.split("\n");
  let [N, K] = lines[0].split(' ').map(s => bigInt(s));

  const mod = N.mod(K)

  console.log(
    bigInt.min(mod, K.minus(mod)).toString()
  );
}

main(require("fs").readFileSync("/dev/stdin", "utf8"));


import { readFileSync } from 'fs'

function main(input: string[]) {
  let [N, K] = input[0].split(' ').map(v=>BigInt(v))
  let amari = N % K;
  let ans = K - amari
  if (amari < ans) ans = amari
  console.log(ans.toString())
}

let lines: string[] = [];
const reader = require('readline').createInterface({
  input: process.stdin,
  output: process.stdout
});

reader.on('line', function (line: string) {
  lines.push(line);
});
reader.on('close', function () {
  main(lines)
});


import * as fs from 'fs';

// main
function main(input: string[]) {
    // param
    var n: number = 0;
    var k: number = 0;
    var ans: number = 0;
    // init
    [n, k] = input.shift().split(" ").map(x => Number(x));
    // solve
    var a = n % k;
    ans = Math.min(a, k - a);
    // answer
    console.log(ans);
}

// graph lib
/*
function GRAPH_enumPattern(cur: number[], pat: number[][]): number[][] {
    var arr = [];
    for (var patx = 0; patx < pat.length; patx++) {
        var pos = [cur[0] + pat[patx][0], cur[1] + pat[patx][1]];
        arr.push(pos);
    }
    return arr;
}
*/

// math lib
/*
function Math_max(arr: number[]): number { return arr.reduce((x, y) => Math.max(x, y)); }
function Math_min(arr: number[]): number { return arr.reduce((x, y) => Math.min(x, y)); }
function Math_gcd(): number {
    var ans = arguments[0];
    var f = (a: number, b: number): number => b ? f(b, a % b) : a
    for (var i = 1; i < arguments.length; i++) {
        ans = f(ans, arguments[i]);
    }
    return ans
};
function Math_gcdArray(values: number[]): number {
    var ans = values[0];
    var f = (a: number, b: number): number => b ? f(b, a % b) : a
    for (var i = 1; i < values.length; i++) {
        ans = f(ans, values[i]);
    }
    return ans
};
function Math_lcm(): number {
    var a = arguments
    var g = (n: number, m: number): number => m ? g(m, n % m) : n
    var l = (n: number, m: number): number => n * m / g(n, m)
    var ans = a[0]
    for (var i = 1; i < a.length; i++) {
        ans = l(ans, a[i])
    }
    return ans
}
function Math_lcmArray(values: number[]): number {
    var a = values
    var g = (n: number, m: number): number => m ? g(m, n % m) : n
    var l = (n: number, m: number): number => n * m / g(n, m)
    var ans = a[0]
    for (var i = 1; i < a.length; i++) {
        ans = l(ans, a[i])
    }
    return ans
}
function Math_primeList(value: number): number[] {
    var ans = [];
    var arr = new Array(value).fill(0);
    for (var i = 2; i < value; i++) {
        if (arr[i] == 0) {
            for (var j = i; j < value; j += i) {
                if (arr[j] == 0) arr[j] = i;
            }
        }
    }
    for (var i = 2; i < value; i++) {
        if (arr[i] == i) ans.push(i);
    }
    return ans;
}
function Math_primeFactor(p: number[], value: number): number[][] {
    var ans: number[][] = [];
    var valmax = value / 2;;
    for (var i = 0; i < p.length; i++) {
        var prime = p[i];
        if (valmax < prime) break;
        var count = 0;
        while (value % prime == 0) {
            value /= prime;
            count++;
        }
        if (count != 0) {
            ans.push([prime, count]);
        }
        if (value == 1) break;
    }
    return ans;
}
*/

// union-find lib
/*
var g_uf_root: number[];
var g_uf_count: number[];
function UF_initRoot(num: number) {
    g_uf_root = new Array(num).fill(-1);
    g_uf_count = new Array(num).fill(1);
}
function UF_getRoot(index: number) {
    if (g_uf_root[index] < 0) {
        return index;
    } else {
        var work0: number = UF_getRoot(g_uf_root[index]);
        g_uf_root[index] = work0;
        return work0
    }
}
function UF_mergeRoot(a: number, b: number) {
    var root0: number = UF_getRoot(a);
    var root1: number = UF_getRoot(b);
    if (root0 == root1) return;
    if (root0 > root1) [root0, root1] = [root1, root0];
    g_uf_count[root0] += g_uf_count[root1];
    g_uf_count[root1] = 0;
    g_uf_root[root1] = root0;
}
*/

// entrypoint
function entrypoint() {
    try {
        // linux
        var input = fs.readFileSync("/dev/stdin", "utf8").trim().split("\n");
        console.debug = function () { };
        main(input);
    }
    catch (ex) {
        // windows
        const lines: string[] = [];
        // @ts-ignore
        const reader = require('readline').createInterface({
            // @ts-ignore
            input: process.stdin,
            // @ts-ignore
            output: process.stdout
        });
        reader.on('line', function (line: string) {
            lines.push(line);
        });
        reader.on('close', function () {
            input = lines;
            main(input);
        });
    }
}
entrypoint();


import { readFileSync } from 'fs'

function main(input: string[]) {
  let [N, K] = input[0].split(' ').map(v=>BigInt(parseInt(v, 10)))
  let amari = N % K;
  let ans = K - amari
  if (amari < ans) ans = amari
  console.log(ans.toString())
}

let lines: string[] = [];
const reader = require('readline').createInterface({
  input: process.stdin,
  output: process.stdout
});

reader.on('line', function (line: string) {
  lines.push(line);
});
reader.on('close', function () {
  main(lines)
});


import { readFileSync } from 'fs'

function main(input: string[]) {
  let [N, K] = input[0].split(' ').map(v=>parseInt(v, 10))
  let ans = 0
  let amari = N % K;
  ans = Math.min(amari, K - amari)
  console.log(ans)
}

let lines: string[] = [];
const reader = require('readline').createInterface({
  input: process.stdin,
  output: process.stdout
});

reader.on('line', function (line: string) {
  lines.push(line);
});
reader.on('close', function () {
  main(lines)
});


str_original = input()
N = len(str_original)
loop = int(N/2)

count = 0
for i in range(loop):
  if str_original[i] != str_original[(N-1)-i]:
     count+= 1

print(count)


S=input()
k=len(S)//2
T=S[:k]
U=S[-k:][::-1]
N=0
for i in range(k):
  if T[i]==U[i]:
     continue
  else:
     N=N+1
print(N)


s=input()
print(sum([a!=b for a,b in zip(s,s[::-1])])//2)


A=input();print(sum(i!=j for i,j in zip(A,A[::-1])//2)


s=input();n=len(s)-1;print(sum(s[i]!=s[n-i]for i in range(n+1))//2)s=input();n=len(s)-1;print(sum(s[i]!=s[n-i]for i in range(n+1))//2)


A=input()
c=0
B=A[::-1]
for i in range(len(A)):
    if A[i]!=B[i]:
        cnt+=1
print(cnt//2)


import java.util.*;
import java.io.*;

class Main{
    public static void main(String[] args){
        FastScanner fsc=new FastScanner();
        char[] c=fsc.next().toCharArray();
        fsc.close();
        int l=c.length;
        int ans=0;
        for(int i=0;i<l/2;i++){
            if(c[i]!=c[l-i-1]) ans++;
        }
        System.out.println(ans);
    }
    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 void close(){
            try{in.close();}
            catch(IOException e){e.printStackTrace();}
        }
    }
}


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

public class Main {

	public static void main(String[] args) {
		FScanner sc = new FScanner();
		String S = sc.next();
		int length = S.length();
		String S1 = "";
		String S2 = "";
		if (length % 2 == 0) {
			S1 = S.substring(0, length / 2);
			S2 = S.substring(length / 2);
		} else {
			S1 = S.substring(0, length / 2);
			S2 = S.substring(length / 2 + 1);
		}
		int cnt = 0;
		char[] c1 = S1.toCharArray();
		char[] c2 = S2.toCharArray();
		for (int i = 0; i < c1.length; i++) {
			if (c1[i] != c2[c2.length - i - 1]) {
				cnt++;
			}
		}
		System.out.println(cnt);
	}

}

class FScanner {
	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 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());
	}
}


import java.io.*;
import java.util.*;
import java.util.function.BiFunction;
import java.util.function.Consumer;
import java.util.function.Supplier;

public class Main {
    final static long MOD07 = 1_000_000_007;
    final static long MOD09 = 1_000_000_009;

    public static void main(String[] args) {
        final FastScanner fs = new FastScanner();
        String S = fs.next();
        int n = S.length();
        int i = 0;
        int j = n-1;

        int count = 0;
        while (i < j) {
            if (S.charAt(i) != S.charAt(j)) {
                count++;
            }
            i++;
            j--;
        }

        PrintWriter out = new PrintWriter(System.out);
        out.println(count);

        out.flush();
    }

    static void debug(Object... os) {
        System.err.println(Arrays.deepToString(os));
    }

    // Execute func for all patterns can be represented with n bit.
    // O(n2^n)
    static void forAllBit(int n, Consumer<List<Boolean>> func) {
        for (int i = 0; i < (1 << n); i++) {
            List<Boolean> arg = new ArrayList();
            for (int j = 0; j < n; j++) {
                boolean isJthBitSet = ((i >> j) & 1) == 1;
                arg.add(isJthBitSet);
            }
            func.accept(arg);
        }
    }

    static class Pair<F extends Comparable<F>, S extends Comparable<S>> implements Comparable<Pair<F, S>> {
        F f;
        S s;

        Pair() {
        }

        Pair(F f, S s) {
            this.f = f;
            this.s = s;
        }

        Pair(Pair<F, S> p) {
            f = p.f;
            s = p.s;
        }

        @Override
        public int compareTo(Pair<F, S> p) {
            if (f.compareTo(p.f) != 0) {
                return f.compareTo(p.f);
            }
            return s.compareTo(p.s);
        }

        @Override
        public int hashCode() {
            return f.hashCode() ^ s.hashCode();
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) {
                return true;
            }
            if (o == null || this.f == null || this.s == null) {
                return false;
            }
            if (this.getClass() != o.getClass()) {
                return false;
            }
            Pair p = (Pair) o;
            return this.f.equals(p.f) && this.s.equals(p.s);
        }

        @Override
        public String toString() {
            return "{" + f.toString() + ", " + s.toString() + "}";
        }
    }

    public static int gcd(int a, int b) {
        if (b == 0) {
            return a;
        }
        return gcd(b, a % b);
    }

    public static boolean isPrime(int n) {
        for (int i = 2; i <= ((int) Math.sqrt(n)); i++) {
            if (n % i == 0) {
                return false;
            }
        }
        return n != 1;
    }

    public static void reverse(int[] array) {
        for (int i = 0; i < array.length / 2; i++) {
            int temp = array[i];
            array[i] = array[array.length - i - 1];
            array[array.length - i - 1] = temp;
        }
    }

    public static void reverse(long[] array) {
        for (int i = 0; i < array.length / 2; i++) {
            long temp = array[i];
            array[i] = array[array.length - i - 1];
            array[array.length - i - 1] = temp;
        }
    }

    public static boolean isPrime(long n) {
        for (long i = 2; i <= ((long) Math.sqrt(n)); i++) {
            if (n % i == 0) {
                return false;
            }
        }
        return n != 1;
    }

    public static Map<Long, Long> primeFactor(long n) {
        Map<Long, Long> map = new HashMap<>();
        long num = n;
        for (long i = 2; i <= ((long) Math.sqrt(n)); i++) {
            while (num % i == 0L) {
                map.put(i, map.getOrDefault(i, 0L) + 1L);
                num /= i;
            }
        }
        if (num != 1) {
            map.put(num, 1L);
        }

        return map;
    }

    public static List<Long> divisors(long n) {
        List<Long> list = new ArrayList<>();
        for (long i = 1; i <= ((long) Math.sqrt(n)); i++) {
            if (n % i == 0) {
                list.add(i);
                if (i != n / i) {
                    list.add(n / i);
                }
            }
        }

        return list;
    }

    public static int lcm(int a, int b) {
        return a / gcd(a, b) * b;
    }

    public static int nCk(int n, int k, int M) {
        long ret = 1;
        int min = Math.min(k, n - k);
        for (int i = 1; i <= min; i++) {
            ret = (ret * pow(i, M - 2, M)) % M;
        }
        for (int i = n - min + 1; i <= n; i++) {
            ret = (ret * i) % M;
        }
        return (int) ret;
    }

    //return a^b mod M O(logB)
    public static long pow(long a, long b, int M) {
        long ret = 1;
        long tmp = a;
        while (b > 0) {
            if ((b & 1) == 1) ret = (ret * tmp) % M;
            tmp = (tmp * tmp) % M;
            b = b >> 1;
        }
        return ret;
    }

    public static int find(int[] tree, int idx) {
        if (tree[idx] == idx) return idx;
        else return tree[idx] = find(tree, tree[idx]);
    }

    public static void union(int[] tree, int idx1, int idx2) {
        int root1 = find(tree, idx1);
        int root2 = find(tree, idx2);
        tree[root2] = root1;
    }

    public static int lowerBound(int[] list, int target) {
        int ok = list.length;
        int ng = -1;
        while (Math.abs(ok - ng) > 1) {
            int mid = (ok + ng) / 2;
            if (list[mid] >= target) {
                ok = mid;
            } else {
                ng = mid;
            }
        }
        return ok;
    }

    public static int lowerBound(long[] list, long target) {
        int ok = list.length;
        int ng = -1;
        while (Math.abs(ok - ng) > 1) {
            int mid = (ok + ng) / 2;
            if (list[mid] >= target) {
                ok = mid;
            } else {
                ng = mid;
            }
        }
        return ok;
    }

    public static <T extends Comparable<? super T>> int lowerBound(List<T> list, T target) {
        return ~Collections.binarySearch(list, target, (x, y) -> (x.compareTo(y) >= 0) ? 1 : -1);
    }

    public static <T extends Comparable<? super T>> int upperBound(List<T> list, T target) {
        return ~Collections.binarySearch(list, target, (x, y) -> (x.compareTo(y) > 0) ? 1 : -1);
    }
}

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 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());
    }
}

class BIT<T> {
    int n;
    ArrayList<T> bit;
    BiFunction<T, T, T> bif;

    /**
     * 1-indexed なBinary Indexed Treeを構築する
     *
     * @param n   容量
     * @param bif 適用させる関数
     * @param sup 初期値
     */
    BIT(int n, BiFunction<T, T, T> bif, Supplier<T> sup) {
        this.n = n;
        bit = new ArrayList<>(n + 1);
        for (int i = 0; i < n + 1; ++i) {
            bit.add(sup.get());
        }
        this.bif = bif;
    }

    /**
     * iの位置の値をvで更新する
     *
     * @param i index
     * @param v 新しい値
     */
    void set(int i, T v) {
        for (int x = i; x <= n; x += x & -x) {
            bit.set(x, bif.apply(bit.get(x), v));
        }
    }

    /**
     * クエリー
     *
     * @param defaultValue 初期値
     * @param i            index
     * @return [1, i]までfを適用した結果
     */
    T reduce(T defaultValue, int i) {
        T ret = defaultValue;
        for (int x = i; x > 0; x -= x & -x) {
            ret = bif.apply(ret, bit.get(x));
        }
        return ret;
    }
}

class SegmentTree<T> {
    int n;
    ArrayList<T> dat;
    BiFunction<T, T, T> bif;
    Supplier<T> sup;

    /**
     * 0-indexed なSegment Treeを構築する
     *
     * @param n_  要求容量
     * @param bif 適用させる関数
     * @param sup 初期値
     */
    SegmentTree(int n_, BiFunction<T, T, T> bif, Supplier<T> sup) {
        n = 1;
        while (n < n_) n *= 2;

        dat = new ArrayList<>(2 * n - 1);
        for (int i = 0; i < 2 * n - 1; ++i) {
            dat.add(sup.get());
        }
        this.bif = bif;
        this.sup = sup;
    }

    /**
     * kの位置の値をvで更新する
     *
     * @param k index
     * @param v 新しい値
     */
    void set(int k, T v) {
        k += n - 1;
        dat.set(k, v);
        while (k > 0) {
            k = (k - 1) / 2;
            dat.set(k, bif.apply(dat.get(k * 2 + 1), dat.get(k * 2 + 2)));
        }
    }

    /**
     * クエリー
     *
     * @param l はじめ
     * @param r おわり
     * @return [l, r)での演算bifを適用した結果を返す
     */
    T reduce(int l, int r) {
        return _reduce(l, r, 0, 0, n);
    }

    T _reduce(int a, int b, int k, int l, int r) {
        if (r <= a || b <= l) return sup.get();
        if (a <= l && r <= b) return dat.get(k);
        T vl = _reduce(a, b, k * 2 + 1, l, (l + r) / 2);
        T vr = _reduce(a, b, k * 2 + 2, (l + r) / 2, r);
        return bif.apply(vl, vr);
    }
}

class UnionFind {
    int[] par;

    UnionFind(int n) {
        par = new int[n];
        for (int i = 0; i < n; ++i) {
            par[i] = i;
        }
    }

    int find(int x) {
        if (par[x] == x) {
            return x;
        }
        return par[x] = find(par[x]);
    }

    boolean same(int x, int y) {
        return find(x) == find(y);
    }

    void union(int x, int y) {
        x = find(x);
        y = find(y);
        if (x == y) {
            return;
        }
        par[x] = y;
    }
}


import java.util.*;

public class Main {
	public static void main(String[] args) throws Exception{
		Scanner scn = new Scanner(System.in);
		String s = scn.next();
		String[] list = s.split("");
      	int count = 0;
		for(int i=0; i<a.length; i++){
			if(!(list[i].equals(list[s.length()-1-i]))) count++;
		}
      	System.out.println(count/2);
	}
}


import java.util.*;
public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    String s = sc.next();
    int leg = s.length();
    String s_l = s.substring(0,leg/2);
    String s_r = s.substring(leg/2);

    int c_l = 0;
    int c_r = leg/2-1;

    int count = 0;

    for(int i = 0 ; i < leg/2 ; ++i){
      if(s_l.charAt(c_l) != s_r.charAt(c_r)){
        count++;
      }
      c_l++;
      c_r--;
    }

    if(leg%2==0 ||count==0){
      System.out.println(count);
    }else{
      System.out.println(count-1);
    }
  }
}


import java.util.*;
public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    String s = sc.next();
    int leg = s.length();
    String s_l = s.substring(0,leg/2);
    String s_r = s.substring(leg/2);

    int c_l = 0;
    int c_r = leg/2-1;

    int count = 0;

    for(int i = 0 ; i < leg/2 ; ++i){
      if(s_l.charAt(c_l) != s_r.charAt(c_r)){
        count++;
      }
      c_l++;
      c_r--;
    }

    if(leg%2==0){
      System.out.println(count);
    }else{
      System.out.println(count-1);
    }
  }
}


#include<cstdio>
#include<algorithm>
#include<functional>
#include<cstring>
using namespace std;
int main(void)
{
	int i,n,cnt,len;
	char s[101];
	scanf("%s",s);
	len=strlen(s);
	cnt=0;
	for(i=0;i<len/2;i++)	{
		if(s[i]!=s[len-i-1])	cnt++;
	}
	printf("%d\n",cnt);
	return 0;
}


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

int main()
{
    string S;

    cin >> S;

    int len = S.length();

    int count = 0;
    rep(i, len / 2)
    {
        if (S.at(i) != S.at(len - i - 1))
        {
            count++;
        }
    }
    cout << count << endl;
}


//   _/                _/                 _/_/_/   _/
//_/_/_/_/   _/_/   _/_/_/_/   _/_/    _/       _/_/
// _/     _/    _/   _/     _/    _/  _/_/_/     _/
//_/     _/    _/   _/     _/    _/  _/    _/   _/
// _/_/   _/_/       _/_/   _/_/      _/_/     _/
#include<iostream>
#include<algorithm>
#include<cmath>
#include<iomanip>
#include<set>
#include<map>
#include<queue>
#include<vector>
using namespace std;
typedef long long ll;
const int MOD=1e9+7;
const double pi=acos(-1);
const int inf=1e9;
int main() {
  cin.tie(0),cout.tie(0);
  ios::sync_with_stdio(false);
  string s;
  cin >> s;
  int ans=0;
  for(int i=0; i<s.size()/2; i++) {
    if(s[i]!=s[s.size()-i-1]) {
      ans++;
    }
  }
  cout << ans << endl;
}


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

int main() {
  string s;
  cin >> s;
  int n = s.size(), ans = 0;
  if(n == 1) {
    cout << 0 << endl;
    return 0;
  }
  else {
    if(n % 2 == 0) {
      rep(i, n/2-1) {
        if(s.at(i) != s.at(n-1-i)) ans++;
      }
    }
    else {
      rep(i, n/2-1) {
        if(s.at(i) != s.at(n-1-i)) ans++;
      }
    }
    cout << ans << endl;
  }
}


#include<bits/stdc++.h>
using namespace std;
int main(void){
  string s,t; cin>>s;
  t=s; reverse(t.begin(),t.end());
  int res=0;
  for(int i=0; i<s.size(); ++i) if(s[i]!=t[i]) ++res;
  cout<<res;
  return 0;
}


#include <bits/stdc++.h>
#define repr(i,a,b) for(int i=a;i<b;i++)
#define rep(i,n) for(int i=0;i<n;i++)
#define reprrev(i,a,b) for(int i=b-1;i>=a;i--) // [a, b)
#define reprev(i,n) reprrev(i,0,n)
#define _GLIBCXX_DEBUG

using ll = long long;
using ull = unsigned long long;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
const ll mod = 1e9+7;
void chmod(ll &M){
  if(M >= mod) M %= mod;
  else if(M < 0){
     M += (abs(M)/mod + 1)*mod;
    M %= mod;
}
}
ll modpow(ll x, ll n){
   if(n==0) return 1;
  ll res=modpow(x, n/2);
 if(n%2==0) return res*res%mod;
else return res*res%mod*x%mod;
}

int getl(int i, int N) { return i==0? N-1:i-1; };
int getr(int i, int N) { return i==N-1? 0:i+1; };
long long GCD(long long a, long long b) {
  if (b == 0) return a;
  else return GCD(b, a % b);
}

using namespace std;

int main() {
  cin.tie(nullptr);
  ios_base::sync_with_stdio(false);
  string S; cin >> S;
  int N = S.length();
  string T;

  rep(i, N) {
    T += S.at(N-1-i);
  }
  cerr << T << " " << S;

  //元の文と回文に比較
  int count = 0;
  rep(i, N) {
    if(T.at(i) != S.at(i)) count++;
  cerr << T.at(i) << " " << S.at(i) << endl;
   }

  cout << count << endl;
}


#include <stdio.h>

int main(void)
{
	char s[101];
	int countChar = 0, countHug = 0;
	int i = 0;

	scanf("%s", s);

	while (s[i])
	{
		countChar++;
		i++;
	}

	for (i = 0; i < countChar / 2; i++)
	{
		if (s[i] != s[countChar - 1 - i])
		{
			countHug++;
		}
	}

	printf("%d\n", countHug);

	return 0;
}


#include<stdio.h>
#include<math.h>
#include<string.h>
#define ll long long int

void sort(ll a[],ll n){

ll i,j,temp;

for(i=0;i<n;i++){

    for(j=0;j<n;j++){

        if(a[i]<a[j]){
            temp=a[i];
            a[i]=a[j];
            a[j]=temp;
        }
    }

}

}

int main(){

char a[100000];
ll i,cnt,n;
cnt=0;

scanf("%s",a);
n=strlen(a);
for(i=0;i<strlen(a)/2;i++)
{
    if(a[i]==a[n-i-1])
    {
        continue;

    }
    else{
        cnt++;
    }

}

printf("%lld",cnt);

return 0;
}


#include <stdio.h>
#include <string.h>
char s[101];
int main(void) {
scanf("%s", s);
int res = 0;
int n = strlen(s);
for (int i = 0; i < n; i++) {
  if (s[i] != s[n - 1 - i]) res++;
  }
	printf("%d\n", res / 2);
}


#include<stdio.h>
#include<string.h>
int main(void){
  char S[200];
  scanf("%s",S);
  int leng;
  leng = strlen(S);
  int i,j;
  j=0;
  for(i=0;i<leng/2 + 1;i++){
    if(S[i]==S[leng-i])
      j++;
  }
  printf("%d",j);
  return 0;
}


#include <stdio.h>

int main()
{
  char s[102];
  int i,n=0,count=0;

  scanf("%s", s);

  for(i=0;;i++){
    if(s[i] !='\0')
      n++;
    else
      break;
    }

  for(i=0; i < n/2; i++)
  {
    if(s[i] != s[n-1-i])
      count++;
  }

  printf("%d",n);
  printf("%d",count );

    return 0;
}


main(){char a[110];int t,i,c=0;scanf("%s",a);t=strlen(a);
for(i=0;i<(t-1)/2;i++){if(a[i]!=a[t-i-1])c++;}printf("%d",c);}


function main(arg) {
	arg = arg.trim();
  	var long = arg.length,
        c = Math.round(long/2),
  		out = 0;
	for (var i = 0; i < c; i ++) {
    	var stword = arg[i],
           	lsword = arg[long - i -1];
      	if (stword != lsword) {
        	out++;
        }
    }
  console.log(out)

}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));


function Main(s) {
  var answer = 0;

  const half = Math.ceil(s.length / 2);
  for (var i = half; i < s.length; i++) {
    if (s[s.length - i - 1] !== s[i]) {
      answer++;
    }
  }

  console.log(answer);
}

Main(require("fs").readFileSync("/dev/stdin", "utf8").trim());


function main(input) {
  var n = input[0];
  var len = n.length;
  var ans = 0;
  for(var i=0;i<Math.trunc(len/2);i++){
    var a = n[i], b=n[len-i-1];
    if(a!=b)ans++;
  }
  console.log(ans);
}
main(require('fs').readFileSync('/dev/stdin', 'utf8').trim().split("\n"))


'use strict';
function main(input) {
  const arr = input.trim().split('\n');
  const a = arr[0];
  const length = a.length;
  let count = 0;

  for (let i = 0; i < Math.ceil(length / 2); i ++) {
    if (a[i] === a[length - 1 - i]) {
      count++;
    }
  }

  console.log(count);
}

main(require("fs").readFileSync("/dev/stdin", "utf8"));


'use strict';
function main(input) {
  const arr = input.trim().split('\n');
  const a = arr[0];
  const length = a.length;
  let count = 0;

  for (let i = 0; i < Math.ceil(length / 2); i ++) {
    if (a[i] === a[length - i]) {
      count++;
    }
  }

  console.log(count);
}

main(require("fs").readFileSync("/dev/stdin", "utf8"));


'use strict';

function Main(input) {
    const str = input.split('');
    let res = 0;
    for ( let i = 0; i < Math.ceil(str.length / 2); i++) {
        if (str[i] !== str[str.length-1-i]) {
            res++;
        }
    }
    console.log(res);
}
// Main(require("fs").readFileSync("/dev/stdin", "utf8"));
Main('redcoder')


package main

import "fmt"

func main() {
	var s string
	fmt.Scan(&s)
	var ret int
	for i := 0; i < len(s)/2; i++ {
		if s[i] != s[len(s)-i-1] {
			ret++
		}
	}
	fmt.Println(ret)
}


package main

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

var sc = bufio.NewScanner(os.Stdin)

func main() {
	sc.Split(bufio.ScanWords)

	s := nextStr()
	if len(s) == 1 {
		fmt.Println("0")
		return
	}
	if IsKaibun(s) == true {
		fmt.Println("0")
		return
	}

	n := len(s)
	diff := 0

	for i := 0; i < n/2; i++ {
		c := s[i]
		if c != s[n-i-1] {
			diff++
		}
	}

	fmt.Println(diff)
}

// IsKaibun return IsKaibun
func IsKaibun(s string) bool {
	n := len(s)

	for i, c := range s {
		if c != rune(s[n-i-1]) {
			return false
		}
	}

	return true
}

// ---- readfunc
func nextInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}
func nextStr() string {
	sc.Scan()
	return sc.Text()
}


package main

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

func solve() {
	s := getRunes()

	ans := 0
	for i := 0; i < len(s)/2; i++ {
		r1 := s[i]
		r2 := s[len(s)-i-1]
		if r1 != r2 {
			ans++
		}
	}

	fmt.Fprintln(wr, ans)
}

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

const (
	inf = 1 << 60
	// mod = 1000000007
)

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

func main() {
	maxBufSize := int(1e8)
	sc.Buffer(make([]byte, 4096), maxBufSize)
	sc.Split(bufio.ScanWords)
	solve()
	wr.Flush()
}

func getInt() (ret int) {
	sc.Scan()
	ret, err := strconv.Atoi(sc.Text())
	if err != nil {
		panic(err)
	}
	return
}

func getIntSlice(n int) (ret []int) {
	ret = make([]int, n)
	for i := range ret {
		ret[i] = getInt()
	}
	return
}

func getString() (ret string) {
	sc.Scan()
	ret = sc.Text()
	return
}

func getRunes() (ret []rune) {
	ret = []rune(getString())
	return
}


package main

import (
	"fmt"
)

func main() {
	var word string
	fmt.Scan(&word)
	palindromeHugger(word)
}

func palindromeHugger(word string) {
	var incidences int
	wordLenght := len(word)

	for i, letter := range word {
		if letter != rune(word[wordLenght-i]) {
			incidences++
		}

		if i == (wordLenght/2)+1 {
			return
		}
	}

	fmt.Println(incidences)
}


package main

import (
	"fmt"
)

func main() {
	var word string
	fmt.Scan(&word)
	palindromeHugger(word)
}

func palindromeHugger(word string) {
	var incidences int
	wordLenght := (len(word) / 2) + 1

	for i, letter := range word {
		if letter != rune(word[wordLenght-i]) {
			incidences++
		}
	}

	fmt.Println(incidences)
}


package main

import (
	"fmt"
)

func main() {
	var word string
	fmt.Scan(&word)
	palindromeHugger(word)
}

func palindromeHugger(word string) {
	var incidences int
	wordLenght := len(word) / 2

	for i, letter := range word {
		if letter != rune(word[wordLenght-i]) {
			incidences++
		}
	}

	fmt.Println(incidences)
}


S = gets.chomp
p (0...S.size/2).inject(0){ |sum, i| sum += S[i] == S.reverse[i] ? 0 : 1}


s = gets.chomp
cnt = 0
for i in 0..(s.length)/2-1 do
  if s[i]!= s[s.length-1-i] then
    cnt += 1
  end
end
puts(cnt)


S=gets.chomp.to_s.chars
count=0

sublength=S.length/2.floor

a=S.shift(sublength)
b=S.pop(sublength).reverse

sublength.times{|n|
    if a[n-1]!=b[n-1]
        count+=1
    end
}

puts count


n=gets.chomp
s=n.reverse
ans=0
for i in 0..((n.size+1)/2)-1
  ans+=1 if n[n]!=s[n]
end
puts ans


S=gets.chars
N=S.size/2

count = 0
N.times{|i|
  count+=1 if S[i] != S[-i-1]
}

p count


S=gets.chars
N=S.size/2

s1,s2=S[0...N],S[-N..-1].reverse

count = 0
N.times{|i|
  count+=1 if s1[i] != s2[i]
}

p count


#![allow(unused_imports)]
use itertools::Itertools;
use proconio::{input, marker::*};
use std::cmp::*;
use std::collections::*;
use superslice::*;
use text_io::read;

fn main() {
    input! {
        s: Chars,
    }

    let n = s.len();
    let bef = Vec::from(&s[0..n / 2]);
    let mut aft = Vec::from(&s[(n + 1) / 2..n]);
    aft.reverse();

    let mut ans = 0;

    for i in 0..n / 2 {
        if bef[i] != aft[i] {
            ans += 1;
        }
    }

    println!("{}", ans);
}


fn main() {
    let s = read::<String>();
    let v: Vec<char> = s.chars().into_iter().collect();
    let n = v.len();

    let mut ret = 0;
    for i in 0..n/2 {
        if v[i] != v[n-1-i] {
            ret += 1;
        }
    }

    println!("{}", ret);
}

fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).unwrap();
    s.trim().parse().ok().unwrap()
}


#![allow(unused_macros, deprecated)]

#[allow(dead_code)]
mod utils {
    use std::io::{
        self, BufRead, BufReader, BufWriter, Seek, SeekFrom, Stdin, StdinLock, Stdout, StdoutLock,
        Write,
    };
    use std::mem;
    use std::ops::{Deref, DerefMut};
    use std::ptr;
    use std::slice;
    use std::str::{self, FromStr};

    #[inline]
    fn is_space_or_line_break(b: &u8) -> bool {
        *b == b' ' || *b == b'\n'
    }

    pub struct Scanner<R: BufRead> {
        reader: R,
        buf: Vec<u8>,
    }

    impl<R: BufRead> Scanner<R> {
        #[inline]
        pub fn new(reader: R) -> Scanner<R> {
            Scanner {
                reader: reader,
                buf: Vec::with_capacity(100),
            }
        }

        pub fn read<T: FromStr>(&mut self) -> T {
            self.read_until(is_space_or_line_break);
            self.parse()
        }

        pub fn read2<T1: FromStr, T2: FromStr>(&mut self) -> (T1, T2) {
            (self.read(), self.read())
        }

        pub fn read3<T1: FromStr, T2: FromStr, T3: FromStr>(&mut self) -> (T1, T2, T3) {
            (self.read(), self.read(), self.read())
        }

        pub fn read4<T1: FromStr, T2: FromStr, T3: FromStr, T4: FromStr>(
            &mut self,
        ) -> (T1, T2, T3, T4) {
            (self.read(), self.read(), self.read(), self.read())
        }

        pub fn reads(&mut self) -> &str {
            self.read_until(is_space_or_line_break);
            unsafe { str::from_utf8_unchecked(&self.buf) }
        }

        pub fn readl(&mut self) -> &str {
            self.buf.clear();
            self.reader.read_until(b'\n', &mut self.buf).unwrap();
            let bytes = if self.buf.last() == Some(&b'\n') {
                &self.buf[..self.buf.len() - 1]
            } else {
                &self.buf
            };
            unsafe { str::from_utf8_unchecked(&bytes) }
        }

        pub fn read_vec<T: FromStr>(&mut self, count: usize) -> Vec<T> {
            (0..count).map(|_| self.read()).collect()
        }

        fn read_until<P: FnMut(&u8) -> bool>(&mut self, mut predicate: P) {
            self.buf.clear();
            let mut first = true;

            // https://doc.rust-lang.org/src/std/io/mod.rs.html#1623-1649
            loop {
                let (done, used) = {
                    let available = self.reader.fill_buf().unwrap();
                    if first && available.len() == 0 {
                        panic!("Scan Error (EOF reached)");
                    }

                    match available.iter().position(&mut predicate) {
                        Some(0) if first => (false, 1),
                        Some(i) => {
                            self.buf.extend_from_slice(&available[..i]);
                            (true, i + 1)
                        }
                        None => {
                            self.buf.extend_from_slice(available);
                            (false, available.len())
                        }
                    }
                };

                self.reader.consume(used);
                if done || used == 0 {
                    return;
                }

                first = false;
            }
        }

        #[inline]
        fn parse<T: FromStr>(&mut self) -> T {
            // 文字列をT型へパースする
            let elem = unsafe { str::from_utf8_unchecked(&self.buf) };
            elem.parse()
                .unwrap_or_else(|_| panic!(format!("failed parsing: {}", elem)))
        }
    }

    impl<R: BufRead + Seek> Seek for Scanner<R> {
        #[inline]
        fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
            self.reader.seek(pos)
        }
    }

    pub struct StdinScanner {
        stdin: Stdin,
        scanner: Scanner<BufReader<StdinLock<'static>>>,
    }

    impl StdinScanner {
        #[inline]
        pub fn new() -> StdinScanner {
            let stdin = io::stdin();
            let stdinlock = unsafe { mem::transmute(stdin.lock()) };
            let reader = BufReader::with_capacity(4096, stdinlock);
            let scanner = Scanner::new(reader);
            StdinScanner {
                stdin: stdin,
                scanner: scanner,
            }
        }
    }

    impl Deref for StdinScanner {
        type Target = Scanner<BufReader<StdinLock<'static>>>;

        #[inline]
        fn deref(&self) -> &Self::Target {
            &self.scanner
        }
    }

    impl DerefMut for StdinScanner {
        #[inline]
        fn deref_mut(&mut self) -> &mut Self::Target {
            &mut self.scanner
        }
    }

    pub struct StdoutWriter {
        stdout: Stdout,
        writer: BufWriter<StdoutLock<'static>>,
    }

    impl StdoutWriter {
        #[inline]
        pub fn new() -> StdoutWriter {
            let stdout = io::stdout();
            let stdoutlock = unsafe { mem::transmute(stdout.lock()) };
            let writer = BufWriter::with_capacity(4096, stdoutlock);
            StdoutWriter {
                stdout: stdout,
                writer: writer,
            }
        }

        pub fn write<T: Writable>(&mut self, v: T) {
            v.display(&mut self.writer);
        }

        pub fn writeln<T: Writable>(&mut self, v: T) {
            v.display(&mut self.writer);
            self.writer.write_all(b"\n").unwrap();
        }

        pub fn write_horizontal<I>(&mut self, iter: I)
        where
            I: IntoIterator,
            I::Item: Writable,
        {
            let mut it = iter.into_iter();
            if let Some(elem) = it.next() {
                elem.display(&mut self.writer);
            } else {
                return;
            }

            for elem in it {
                elem.display(&mut self.writer);
                self.writer.write_all(b" ").unwrap();
            }
        }

        pub fn write_vertical<I>(&mut self, iter: I)
        where
            I: IntoIterator,
            I::Item: Writable,
        {
            let mut it = iter.into_iter();
            if let Some(elem) = it.next() {
                elem.display(&mut self.writer);
            } else {
                return;
            }

            for elem in it {
                elem.display(&mut self.writer);
                self.writer.write_all(b"\n").unwrap();
            }
        }
    }

    impl Write for StdoutWriter {
        #[inline]
        fn flush(&mut self) -> io::Result<()> {
            self.writer.flush()
        }

        #[inline]
        fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
            self.writer.write(buf)
        }
    }

    static DEC_DIGITS_LUT: &'static [u8; 200] = b"0001020304050607080910111213141516171819\
            2021222324252627282930313233343536373839\
            4041424344454647484950515253545556575859\
            6061626364656667686970717273747576777879\
            8081828384858687888990919293949596979899";

    fn write_int<W: Write>(mut writer: W, mut n: u64, is_negative: bool) {
        unsafe {
            let mut buf: [u8; 39] = mem::uninitialized();
            let buf_ptr_start = buf.as_mut_ptr().offset(39);
            let mut buf_ptr = buf_ptr_start;
            let lut_ptr = DEC_DIGITS_LUT.as_ptr();

            while n >= 10000 {
                let rem = (n % 10000) as isize;
                n /= 10000;

                let d1 = (rem / 100) << 1;
                let d2 = (rem % 100) << 1;
                buf_ptr = buf_ptr.offset(-4);
                ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr, 2);
                ptr::copy_nonoverlapping(lut_ptr.offset(d2), buf_ptr.offset(2), 2);
            }

            let mut n = n as isize; // possibly reduce 64bit math

            // decode 2 more chars, if > 2 chars
            if n >= 100 {
                let d1 = (n % 100) << 1;
                n /= 100;
                buf_ptr = buf_ptr.offset(-2);
                ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr, 2);
            }

            // decode last 1 or 2 chars
            if n < 10 {
                buf_ptr = buf_ptr.offset(-1);
                *buf_ptr = (n as u8) + b'0';
            } else {
                let d1 = n << 1;
                buf_ptr = buf_ptr.offset(-2);
                ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr, 2);
            }

            if is_negative {
                buf_ptr = buf_ptr.offset(-1);
                *buf_ptr = b'-';
            }

            let buf_slice =
                slice::from_raw_parts(buf_ptr, buf_ptr_start as usize - buf_ptr as usize);

            writer.write_all(buf_slice).unwrap();
        }
    }

    pub trait Writable {
        fn display<W: Write>(&self, writer: &mut W);
    }

    impl Writable for str {
        #[inline]
        fn display<W: Write>(&self, writer: &mut W) {
            writer.write_all(self.as_bytes()).unwrap()
        }
    }

    impl<'a> Writable for &'a str {
        #[inline]
        fn display<W: Write>(&self, writer: &mut W) {
            writer.write_all(self.as_bytes()).unwrap()
        }
    }

    impl Writable for String {
        #[inline]
        fn display<W: Write>(&self, writer: &mut W) {
            writer.write_all(self.as_bytes()).unwrap()
        }
    }

    impl Writable for bool {
        #[inline]
        fn display<W: Write>(&self, writer: &mut W) {
            let s: &'static [u8] = if *self { b"Yes" } else { b"No" };
            writer.write_all(s).unwrap();
        }
    }

    macro_rules! impl_writable_int {
        ($($int:ty)*) => {
            $(
                impl Writable for $int {
                    #[allow(unused_comparisons)]
                    fn display<W: Write>(&self, writer: &mut W) {
                        let is_negative = !(*self >= 0);
                        let abs = if is_negative {
                            (!*self as u64).wrapping_add(1)
                        } else {
                            *self as u64
                        };
                        write_int(writer, abs, is_negative);
                    }
                }
            )*
        };
    }

    macro_rules! impl_writable_float {
        ($($float:ty)*) => {
            $(
                impl Writable for $float {
                    #[inline]
                    fn display<W: Write>(&self, writer: &mut W) {
                        write!(writer, "{}", *self).unwrap();
                    }
                }
            )*
        }
    }

    impl_writable_int!(u8 u16 u32 u64 usize i8 i16 i32 i64 isize);
    impl_writable_float!(f32 f64);

    pub static mut SCANNER: *mut StdinScanner = 0 as *mut StdinScanner;
    pub static mut WRITER: *mut StdoutWriter = 0 as *mut StdoutWriter;

    #[inline]
    pub fn atcoder_initialize() {
        unsafe {
            SCANNER = mem::transmute(Box::new(StdinScanner::new()));
            WRITER = mem::transmute(Box::new(StdoutWriter::new()));
        }
    }

    #[inline]
    pub fn atcoder_finish() {
        unsafe {
            (*WRITER).flush().unwrap();
        }
    }
}

macro_rules! input {
    () => {};
    (@scanner $scanner:ident, @pred [ $($pred:tt)* ], ($var1:tt, $var2:tt) : [($t1:tt, $t2:tt) ; $len:expr]) => {
        let mut $var1 = Vec::with_capacity($len as usize);
        let mut $var2 = Vec::with_capacity($len as usize);

        for _ in 0..$len {
            $var1.push(scan!($scanner, $t1));
            $var2.push(scan!($scanner, $t2));
        }
    };
    (@scanner $scanner:ident, @pred [ $($pred:tt)* ], $var:tt : $t:tt) => {
        let $($pred)* $var = scan!($scanner, $t);
    };
    (@scanner $scanner:ident,) => {};
    (@scanner $scanner:ident, $var:tt : $t:tt) => {
        input!(@scanner $scanner, @pred [], $var : $t);
    };
    (@scanner $scanner:ident, mut $var:tt : $t:tt) => {
        input!(@scanner $scanner, @pred [mut], $var : $t);
    };
    (@scanner $scanner:ident, $var:tt : $t:tt, $($r:tt)*) => {
        input!(@scanner $scanner, $var : $t);
        input!(@scanner $scanner, $($r)*);
    };
    (@scanner $scanner:ident, mut $var:tt : $t:tt, $($r:tt)*) => {
        input!(@scanner $scanner, mut $var : $t);
        input!(@scanner $scanner, $($r)*);
    };
    ($($r:tt)*) => {
        let scanner_ref = unsafe { &mut *$crate::utils::SCANNER };
        input!(@scanner scanner_ref, $($r)*);
    }
}

macro_rules! scan {
    ($scanner:ident, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| scan!($scanner, $t)).collect::<Vec<_>>()
    };
    ($scanner:ident, usize1) => {
        scan!($scanner, usize) - 1
    };
    ($scanner:ident, line) => {
        $scanner.readl().to_string()
    };
    ($scanner:ident, $t:ty) => {
        $scanner.read::<$t>()
    };
}

macro_rules! pprint {
    ($value:expr) => {
        unsafe {
            (*$crate::utils::WRITER).write($value);
        }
    };
    ($value:expr, $($r:tt)*) => {
        let writer = unsafe { &*$crate::utils::WRITER };
        writer.write($value);
        writer.write(" ");
        pprint!($($r)*);
    };
}

macro_rules! pprintln {
    ($value:expr) => {
        unsafe {
            (*$crate::utils::WRITER).writeln($value);
        }
    };
    ($value:expr, $($r:tt)*) => {
        let writer = unsafe { &*$crate::utils::WRITER };
        writer.write($value);
        writer.write(" ");
        pprintln!($($r)*);
    };
}

macro_rules! atcoder_main {
    ($func:ident) => {
        fn main() {
            $crate::utils::atcoder_initialize();
            $func();
            $crate::utils::atcoder_finish();
        }
    };
}

fn run() {
    input! {
        s: line
    }

    let s = s.into_bytes();
    let mut count = 0;

    for i in 0..s.len() / 2 {
        if s[i] != s[s.len() - i - 1] {
            count += 1;
        }
    }

    pprintln!(count);
}

atcoder_main!(run);


// Vicfred
// https://atcoder.jp/contests/abc147/tasks/abc147_b
// string manipulation
use std::io;

fn main() {
    let mut s = String::new();

    io::stdin()
        .read_line(&mut s)
        .unwrap();

    let s = s.trim();

    let n = s.len();
    let s: Vec<char> = s.chars().collect();

    let mut answer = 0;

    for i in 0..n-1 as usize {
        if s[i] != s[n-i-1] {
            answer += 1;
        }
    }

    println!("{}", answer/2);

}


// Vicfred
// https://atcoder.jp/contests/abc147/tasks/abc147_b
// string manipulation
use std::io;

fn main() {
    let mut s = String::new();

    io::stdin()
        .read_line(&mut s)
        .unwrap();

    let s = s.trim();

    let n = s.len();
    let s: Vec<char> = s.chars().collect();

    let mut answer = 0;

    for i in 0..n-1 as usize {
        if s[i] != s[n-i-1] {
            answer += 1;
        }
    }

    println!("{}", answer);

}


// Vicfred
// https://atcoder.jp/contests/abc147/tasks/abc147_b
// string manipulation
use std::io;

fn main() {
    let mut s = String::new();

    io::stdin()
        .read_line(&mut s)
        .unwrap();

    let s = s.trim();

    let n = s.len();
    let s: Vec<char> = s.chars().collect();

    let mut answer = 0;

    for i in 0..n-1 as usize {
        println!("{}", i);
        if s[i] != s[n-i-1] {
            answer += 1;
        }
    }

    println!("{}", answer);

}


import Foundation

func readInts() -> [Int] {
    return readLine()!.split(separator: " ").map { Int($0)! }
}

let S=readLine()!

var diff=0

var i=0

for _ in S{
  let c1=S[S.index(S.startIndex,offsetBy:i)]
  let c2=S[S.index(S.endIndex,offsetBy:-i-1)]
  if c1 != c2{diff+=1}
  i+=1
}

print(diff/2)


let arr=Array(readLine()!.characters)

var i = 0
var ans = 0
while ( i < arr.count / 2 ) {
  if(arr[i] != arr[arr.count-i-1]) {
    ans += 1
  }
  i+=1
}

print(ans)


import Foundation

func readInts() -> [Int] {
    return readLine()!.split(separator: " ").map { Int($0)! }
}
func main() {
    let S = Array(readLine()!)
    var ans = 0
    for i in stride(from: 0, to: S.count/2, by: 1){
        if S[i] != S[S.count-i-1]{
            ans += 1
        }
    }
    print(ans)
}
main()


let s=readLine()!
let n=s.count
var S=Array(s)
var count=0
if n%2==0{
  for i in 0...n/2-1{
    if S[i] != S[-1-i]{
      count+=1
    }
  }
}else{
   for i in 0...(n-1)/2-1{
    if S[i] != S[-1-i]{
      count+=1
    }
  }
}
print(count)


import * as fs from 'fs';

//in
// abcdabc
//out
// 2
const main = (inp: string) => {
    let ans: number = 0;

    for (let i = 0; i < Math.floor(inp.length / 2); i++) {
        if (inp[i] !== inp[inp.length - i - 1]) {
            ans++;
        }
    }
    console.log(ans);
};

main(fs.readFileSync('/dev/stdin', 'utf8').trim());


function Main(input: string) {

    let target = input.split('\n')[0].split('');
    let center = Math.floor(target.length / 2);
    let count = 0;

    target.some((v, i, arr) => {
        if (i >= center) {
            return true;
        }
        if (v !== arr[(target.length - 1) - i]) {
            count++;
        }
    })

    console.log(count)

}

Main(require('fs').readFileSync('/dev/stdin', 'utf8'));


function main(input: string) {
  const S = input.split("");
  let c = 0;
  for(let i = 0, bi = S.length - 1, l = Math.ceil(S.length / 2); i < l; i++, bi--) {
    if (S[i] !== S[bi]) c++
  }
  console.log(c);
}

main(
  require("fs")
    .readFileSync("/dev/stdin", "utf8")
    .trim()
);


import * as fs from 'fs';

//in
// abcdabc
//out
// 2
const main = (inp: string) => {
    let ans: number = 0;

    for (let i = 0; i < Math.floor(inp.length / 2); i++) {
        console.log(`${inp[i]}  ${inp[inp.length - i - 1]}`);
        if (inp[i] !== inp[inp.length - i - 1]) {
            ans++;
        }
    }
    console.log(ans);
};

main(fs.readFileSync('/dev/stdin', 'utf8').trim());


import * as fs from "fs";

const input = (fs.readFileSync("/dev/stdin", "utf8") as string).split("\n");
//const n = +input[0];
//const a = [];
//for(let i=0;i<n;i++){
//	a.push(input[i+1].split(" ").map((x:string):number=>+x));
//}

//const [n, m] = input[0].split(" ").map((x: string): number => +x);
//const a = input[1].split(" ").map((x: string): number => +x);

function compareFunc(a, b){
    return a-b;
}

const s: string[] = input[0].split('');
const ss: string[] = s.slice().reverse();

let ans: number = 0;
const len: number = Math.floor(s.length/2)
for(let i = 0; i < len; i++){
    if(s[i] !== ss[i]){
        ans++
    }
    console.log(s[i],ss[i]);
}
console.log(ans);


const fs = require('fs');

const main = () => {

    const input: string = fs.readFileSync('/dev/stdin', 'utf8');
  	const inputArr = input.split("");
    let hugs = 0;
    for (let i = 0; i < Math.ceil(inputArr.length/2); i++) {
        if (inputArr[i] != inputArr[inputArr.length-1-i]) {
            hugs++;
        }
    }
    console.log(hugs);
};

main();


N = int(input())
Slist = input().split()
A = Slist[0]
B = Slist[1]

for i in range (N):
	print(A[i],B[i], end='',sep='')


N = int(input())
S, T = input().split()
ans = ''
for s, t in zip(S, T):
    ans += s + t
print(ans)


n = int(input())
s,t = input().split()
new = ''
for i in range(n):
    new += s[i]
    new += t[i]
print(new)


n=int(input())
s,t=input().split()
ans=0
for i in range(n):
    ans=ans+s[i]+t[i]
print(ans)


n=int(input())
ans=s[0]+t[0]
s,t=input().split()
for i in range(1,n):
    ans=ans+s[i]+t[i]
print(ans)


n=int(input().split())
ans=s[0]+t[0]
s,t=input().split()
for i in range(1,n):
    ans=ans+s[i]+t[i]
print(ans)


import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;
import java.util.NoSuchElementException;

public class Main {

	public static void main(String[] args) {

		long mod=1000*1000*1000+7;

		FastScanner sc = new FastScanner();
		PrintWriter out = new PrintWriter(System.out);

		long N=sc.nextLong();
		String S=sc.next();
		String T=sc.next();

		for(int i=0;i<N;i++) {
			out.print(S.charAt(i));
			out.print(T.charAt(i));
		}

		out.flush();
	}
}

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 int[] nextIntsN(int N) {
		int[] ints = new int[N];
		for (int i = 0; i < N; i++) {
			ints[i] = nextInt();
		}
		return ints;
	}

	public long[] nextLongsN(int N) {
		long[] longs = new long[N];
		for (int i = 0; i < N; i++) {
			longs[i] = nextLong();
		}
		return longs;
	}

	public char[] nextCharsN(int N) {
		char[] chars = new char[N];
		String msg = next();
		for (int i = 0; i < N; i++) {
			chars[i] = msg.charAt(i);
		}
		return chars;
	}

	public char[][] nextCharsHW(int H, int W) {
		char[][] chars = new char[H][W];
		for (int i = 0; i < H; i++) {
			String str = next();
			for (int j = 0; j < W; j++) {
				chars[i][j] = str.charAt(j);
			}
		}
		return chars;
	}

	public int[][] nextIntsNM(int N, int M) {
		int[][] ints = new int[N][M];
		for (int i = 0; i < N; i++) {
			for (int j = 0; j < M; j++) {
				ints[i][j] = nextInt();
			}
		}
		return ints;
	}

	public List<Integer> nextArrayIntsN(int N) {
		ArrayList<Integer> array = new ArrayList<>(N);
		for (int i = 0; i < N; i++) {
			array.add(nextInt());
		}
		return array;
	}

	public List<Long> nextArrayLongsN(int N) {
		ArrayList<Long> array = new ArrayList<>(N);
		for (int i = 0; i < N; i++) {
			array.add(nextLong());
		}
		return array;
	}

	public List<List<Long>> nextArrayLongsNM(int N, int M) {

		List<List<Long>> arrays = new ArrayList<List<Long>>(M);
		for (int i = 0; i < M; i++) {
			List<Long> array = nextArrayLongsN(N);
			arrays.add(array);
		}
		return arrays;
	}

}