Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
If your opponent controls more monsters than you do, you can Special Summon this card (from your hand).
--ヴェルズ・マンドラゴ
--Evilswarm Mandragora
local s,id=GetID()
function s.initial_effect(c)
	--special summon
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_FIELD)
	e1:SetCode(EFFECT_SPSUMMON_PROC)
	e1:SetProperty(EFFECT_FLAG_UNCOPYABLE)
	e1:SetRange(LOCATION_HAND)
	e1:SetCondition(s.spcon)
	c:RegisterEffect(e1)
end
function s.spcon(e,c)
	if c==nil then return true end
	return Duel.GetLocationCount(c:GetControler(),LOCATION_MZONE)>0
		and Duel.GetFieldGroupCount(c:GetControler(),LOCATION_MZONE,0,nil)<Duel.GetFieldGroupCount(c:GetControler(),0,LOCATION_MZONE,nil)
end