def solve():
    n = int(input())
    a = [int(x) for x in input().split()]
    if 0 <= min(a):
        a.sort()
        print(a[0] * a[-1])
    elif max(a) <= 0:
        a.sort(reverse=True)
        print(a[0] * a[-1])
    else:
        pa = min(x for x in a if x >= 0)
        ma = max(x for x in a if x <= 0)
        print(pa * ma)

t = int(input())
for i in range(t):
    solve()