def main():
	t = int(input())
	for _ in range(t):
		solve()
		
		
def solve():
	n = int(input())
	a = list(map(int, input().split()))
	plus = []
	z = 0
	minus = []
	for v in a:
		if v < 0:
			minus.append(-v)
		elif v==0:
			z += 1 
		else:
			plus.append(v)
	minus.sort()
	plus.sort()
	if z:
		print(0)
		return
	if minus and plus:
		print(-minus[0]*plus[0])
		return
	elif plus:
		print(plus[0]*plus[-1])
		return
	elif minus:
		print(minus[0]*minus[-1])
		return
	assert(0==1)
	
	
if __name__ == "__main__":
	main()