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

    if(0 in A):
        print(0)
    elif(A[0] > 0):
        print(A[0] * A[1])
    else:
        minus_max = max(i for i in A if i < 0)
        plus_min = min(i for i in A if i > 0)
        print(minus_max * plus_min)