Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
All other monsters on the field lose 500 ATK. Once per turn, during your Main Phase: You can destroy all monsters on the field with less ATK than this card.
--猛虎モンフー
--Fierce Tiger Monghu
--scripted by pyrQ
local s,id=GetID()
function s.initial_effect(c)
	--Decrease ATK
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_FIELD)
	e1:SetCode(EFFECT_UPDATE_ATTACK)
	e1:SetRange(LOCATION_MZONE)
	e1:SetTargetRange(LOCATION_MZONE,LOCATION_MZONE)
	e1:SetTarget(function(e,c) return c~=e:GetHandler() end)
	e1:SetValue(-500)
	c:RegisterEffect(e1)
	--Destroy all monsters with less ATK
	local e2=Effect.CreateEffect(c)
	e2:SetDescription(aux.Stringid(id,0))
	e2:SetCategory(CATEGORY_DESTROY)
	e2:SetType(EFFECT_TYPE_IGNITION)
	e2:SetRange(LOCATION_MZONE)
	e2:SetCountLimit(1)
	e2:SetTarget(s.destg)
	e2:SetOperation(s.desop)
	c:RegisterEffect(e2)
end
function s.desfilter(c,atk)
	return c:IsFaceup() and c:GetAttack()<atk
end
function s.destg(e,tp,eg,ep,ev,re,r,rp,chk)
	local g=Duel.GetMatchingGroup(s.desfilter,tp,LOCATION_MZONE,LOCATION_MZONE,nil,e:GetHandler():GetAttack())
	if chk==0 then return #g>0 end
	Duel.SetOperationInfo(0,CATEGORY_DESTROY,g,#g,0,0)
end
function s.desop(e,tp,eg,ep,ev,re,r,rp)
	local c=e:GetHandler()
	if not (c:IsRelateToEffect(e) and c:IsFaceup()) then return end
	local g=Duel.GetMatchingGroup(s.desfilter,tp,LOCATION_MZONE,LOCATION_MZONE,nil,c:GetAttack())
	if #g==0 then return end
	Duel.Destroy(g,REASON_EFFECT)
end