t = int(input())

for _ in range(t):
    n = int(input())
    a = list(map(int, input().split()))
    
    pos = [x for x in a if x > 0]
    neg = [x for x in a if x < 0]
    zeros = a.count(0)

    if zeros >= 1:
        print(0)
    elif pos and neg:
        print(min(pos) * max(neg))
    elif neg == []:
        print(min(pos) * max(pos))