T=int(input())
for _ in range(T):
	n=int(input())
	a=list(map(int,input().split()))
	if 0 in a:
		print(0)
		continue
	if min(a)*max(a)>0:
		print(min(a)*max(a))
	else:
		print(min(v for v in a if v>0)*max(v for v in a if v<0))