def solve():
    N = int(input())
    A = [int(a) for a in input().split()]

    minus = [a for a in A if a <= 0]
    plus = [a for a in A if a >= 0]

    if len(minus) == 0 or len(plus) == 0:
        print(min(A) * max(A))
    else:
        print(min(plus) * max(minus))


if __name__ == "__main__":
    T = int(input())
    for _ in range(T):
        solve()