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

    plus = []
    minus = []
    flag = False
    for a in A:
        if a == 0:
            print(0)
            flag = True
            break
        elif 0 < a:
            plus.append(a)
        else:
            minus.append(-a)
    if flag:
        continue
    if not minus:
        print(min(plus)*max(plus))
    elif not plus:
        print(min(minus)*max(minus))
    else:
        print(-(min(minus)*min(plus)))