Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
When this card is Normal Summoned, if your opponent controls a monster and you control no other monsters: You can target 1 Set Spell/Trap Card on the field; destroy that target.
--幻角獣フュプノコーン
--Hypnocorn
local s,id=GetID()
function s.initial_effect(c)
	--destroy
	local e3=Effect.CreateEffect(c)
	e3:SetDescription(aux.Stringid(id,0))
	e3:SetCategory(CATEGORY_DESTROY)
	e3:SetType(EFFECT_TYPE_SINGLE+EFFECT_TYPE_TRIGGER_O)
	e3:SetCode(EVENT_SUMMON_SUCCESS)
	e3:SetProperty(EFFECT_FLAG_CARD_TARGET)
	e3:SetCondition(s.descon)
	e3:SetTarget(s.destg)
	e3:SetOperation(s.desop)
	c:RegisterEffect(e3)
end
function s.descon(e,tp,eg,ep,ev,re,r,rp)
	return Duel.GetFieldGroupCount(tp,LOCATION_MZONE,0)<=1 and Duel.GetFieldGroupCount(tp,0,LOCATION_MZONE)>0
end
function s.filter(c)
	return c:IsFacedown()
end
function s.destg(e,tp,eg,ep,ev,re,r,rp,chk,chkc)
	if chkc then return chkc:IsLocation(LOCATION_SZONE) and s.filter(chkc) end
	if chk==0 then return Duel.IsExistingTarget(s.filter,tp,LOCATION_SZONE,LOCATION_SZONE,1,nil) end
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_DESTROY)
	local g=Duel.SelectTarget(tp,s.filter,tp,LOCATION_SZONE,LOCATION_SZONE,1,1,nil)
	Duel.SetOperationInfo(0,CATEGORY_DESTROY,g,1,0,0)
end
function s.desop(e,tp,eg,ep,ev,re,r,rp)
	local tc=Duel.GetFirstTarget()
	if tc:IsFacedown() and tc:IsRelateToEffect(e) then
		Duel.Destroy(tc,REASON_EFFECT)
	end
end