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

    if pos and neg:
        print(pos[0] * neg[-1])  
    elif len(neg) > 1:
        print(neg[0] * neg[-1])
    elif len(pos) > 1:
        print(pos[0] * pos[-1])