import sys
input = sys.stdin.readline

T = int(input())
for _ in range(T):
    N = int(input())
    A = list(map(int, input().split()))

    has_zero = False
    has_pos = False
    has_neg = False

    minA = 10**30
    maxA = -10**30
    min_pos = 10**30
    max_neg = -10**30

    for x in A:
        if x == 0:
            has_zero = True
        if x > 0:
            has_pos = True
            min_pos = min(min_pos, x)
        if x < 0:
            has_neg = True
            max_neg = max(max_neg, x)
        minA = min(minA, x)
        maxA = max(maxA, x)

    if has_zero:
        print(0)
    elif not has_pos or not has_neg:
        print(minA * maxA)
    else:
        print(min_pos * max_neg)