import sys
input = sys.stdin.readline
T = int(input())
INF = 10**9+7
for _ in range(T):
    N = int(input())
    A = list(map(int, input().split()))
    A.sort()
    if A[0]>=0:
        ans = A[0]*A[-1]
    elif A[-1]<0:
        ans = A[0]*A[-1]
    else:
        fu = -INF
        sei = INF
        for a in A:
            if a<0:
                fu = max(fu, a)
            if a>=0:
                sei  =min(sei, a)
        ans = fu*sei
    print(ans)