T = int(input())
for _ in range(T):
    N = int(input())
    A = list(map(int, input().split()))
    A.sort()
    plus = [a for a in A if a >= 0]
    minus = [a for a in A if a < 0]
    if len(minus) == 0:
        print(plus[0] * plus[-1])
    elif len(plus) == 0:
        print(minus[0] * minus[-1])
    elif len(minus) == 1:
        print(minus[0] * plus[0])
    else:
        print(minus[-1] * plus[0])