from collections import deque, defaultdict, Counter
from bisect import bisect_left, bisect_right
from itertools import permutations, combinations
from heapq import heappop, heappush
import math, sys
input = lambda: sys.stdin.readline().rstrip("\r\n")
_int = lambda x: int(x)-1
MOD = 998244353 #10**9+7
INF = 1<<60
Yes, No = "Yes", "No"

T = int(input())

for _ in range(T):
    N = int(input())
    A = list(map(int, input().split()))
    p = []
    n = []
    for a in A:
        if a <= 0: n.append(a)
        else: p.append(a)
    p.sort()
    n.sort()
    if len(n) == 0:
        print(p[0]*p[-1])
    elif len(p) == 0:
        print(n[0]*n[-1])
    else:
        print(p[0]*n[-1])