def solve() :
	N = int(input())
	A = [int(x) for x in input().split()]
	if max(A) <= 0 or min(A) >= 0 :
		print(max(A) * min(A))
	else :
		a = 10 ** 9
		b = -(10 ** 9)
		for x in A :
			if x >= 0 :
				a = min(a, x)
			else :
				b = max(b, x)
		print(a * b)
T = int(input())
for _ in range(T) :
	solve()