if redis.call("exist",KEYS[1] == 1) 
then 
	local productNum =tonumber(redis.call("get",KEYS[1]))
	local subNum = tonumber(ARGV[1])

	if(productNum <= 0)
	then
	return -4
	end

	if(subNum >= 0)
	then 
	return -1
	end

	if(productNum + subNum >=0)
	then
	return redis.call("INCRBY",KYES[1],0 + subNum)
	end

	return -2
end
return -3