T = int(input())

for _ in range(T):
	m = []
	p = []
	N = int(input())
	A = list(map(int,input().split()))
	if 0 in A:
		print(0)
		continue
	for i in range(N):
		if A[i] > 0:
			p.append(A[i])
		else:
			m.append(A[i])
	if p == []:
		print(max(m) * min(m))
		continue
	if m == []:
		print(max(p) * min(p))
		continue
	print(min(p) * max(m))