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 neg == []:
        print(pos[0] * pos[1])
        continue
    
    if pos == []:
        print(neg[-1] * neg[-2])
        continue
    
    cand1 = neg[-1] * pos[0]
    cand2 = neg[0] * pos[-1]
    print(max(cand1, cand2))