Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
Place 1 A-Counter on all monsters Special Summoned to your opponent's side of the field. (If a monster with an A-Counter battles an "Alien" monster, it loses 300 ATK and DEF for each A-Counter during damage calculation only.)
--エーリアン・キッズ
--Alien Kid
local s,id=GetID()
function s.initial_effect(c)
	--counter
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_FIELD+EFFECT_TYPE_CONTINUOUS)
	e1:SetRange(LOCATION_MZONE)
	e1:SetCode(EVENT_SPSUMMON_SUCCESS)
	e1:SetOperation(s.ctop)
	c:RegisterEffect(e1)
	--atk def
	local e2=Effect.CreateEffect(c)
	e2:SetType(EFFECT_TYPE_FIELD)
	e2:SetCode(EFFECT_UPDATE_ATTACK)
	e2:SetRange(LOCATION_MZONE)
	e2:SetTargetRange(LOCATION_MZONE,LOCATION_MZONE)
	e2:SetCondition(s.adcon)
	e2:SetTarget(s.adtg)
	e2:SetValue(s.adval)
	c:RegisterEffect(e2)
	local e3=e2:Clone()
	e3:SetCode(EFFECT_UPDATE_DEFENSE)
	c:RegisterEffect(e3)
end
s.listed_series={SET_ALIEN}
s.counter_place_list={COUNTER_A}
function s.ctop(e,tp,eg,ep,ev,re,r,rp)
	local tc=eg:GetFirst()
	for tc in aux.Next(eg) do
		if tc:IsFaceup() and tc:IsControler(1-tp) then
			tc:AddCounter(COUNTER_A,1)
		end
	end
end
function s.adcon(e)
	return Duel.IsPhase(PHASE_DAMAGE_CAL) and Duel.GetAttackTarget()
end
function s.adtg(e,c)
	local bc=c:GetBattleTarget()
	return bc and c:GetCounter(COUNTER_A)~=0 and bc:IsSetCard(SET_ALIEN)
end
function s.adval(e,c)
	return c:GetCounter(COUNTER_A)*-300
end