def solve():
	INF = 10**18
	N = int(input())
	A = list(map(int, input().split()))
	M = max(A)
	m = min(A)
	if 0 in A:
		print(0)
	else:
		if M > 0 and m > 0:
			print(M * m)
		elif M < 0 and m < 0:
			print(M * m)
		else:
			p, q = -INF, INF
			for a in A:
				if a < 0: p = max(p, a)
				else: q = min(q, a)
			print(p*q)

for _ in range(int(input())): solve()