Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
If this card is Normal or Special Summoned: You can target up to 2 other cards on the field; destroy them, and if you do, this card gains 600 ATK for each card destroyed. You can only use this effect of "Grandtusk Dragon" once per turn.
--グランドタスク・ドラゴン
--Grandtusk Dragon
--scripted by Naim
local s,id=GetID()
function s.initial_effect(c)
	--Destroy up to 2 cards and increase ATK
	local e1=Effect.CreateEffect(c)
	e1:SetDescription(aux.Stringid(id,0))
	e1:SetCategory(CATEGORY_DESTROY+CATEGORY_ATKCHANGE)
	e1:SetType(EFFECT_TYPE_SINGLE+EFFECT_TYPE_TRIGGER_O)
	e1:SetProperty(EFFECT_FLAG_CARD_TARGET+EFFECT_FLAG_DELAY)
	e1:SetCode(EVENT_SUMMON_SUCCESS)
	e1:SetCountLimit(1,id)
	e1:SetTarget(s.destg)
	e1:SetOperation(s.desop)
	c:RegisterEffect(e1)
	local e2=e1:Clone()
	e2:SetCode(EVENT_SPSUMMON_SUCCESS)
	c:RegisterEffect(e2)
end
function s.destg(e,tp,eg,ep,ev,re,r,rp,chk,chkc)
	local c=e:GetHandler()
	if chkc then return chkc~=c and chkc:IsOnField() end
	if chk==0 then return Duel.IsExistingTarget(nil,tp,LOCATION_ONFIELD,LOCATION_ONFIELD,1,c) end
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_DESTROY)
	local g=Duel.SelectTarget(tp,nil,tp,LOCATION_ONFIELD,LOCATION_ONFIELD,1,2,c)
	Duel.SetOperationInfo(0,CATEGORY_DESTROY,g,#g,0,0)
end
function s.desop(e,tp,eg,ep,ev,re,r,rp)
	local g=Duel.GetTargetCards(e)
	if #g==0 then return end
	local ct=Duel.Destroy(g,REASON_EFFECT)
	local c=e:GetHandler()
	if ct>0 and c:IsFaceup() and c:IsRelateToEffect(e) then
		--Increase ATK
		local e1=Effect.CreateEffect(c)
		e1:SetType(EFFECT_TYPE_SINGLE)
		e1:SetProperty(EFFECT_FLAG_SINGLE_RANGE)
		e1:SetRange(LOCATION_MZONE)
		e1:SetCode(EFFECT_UPDATE_ATTACK)
		e1:SetValue(ct*600)
		e1:SetReset(RESET_EVENT|RESETS_STANDARD_DISABLE)
		c:RegisterEffect(e1)
	end
end