#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;

using isize = size_t;
using i32 = int;
using u32 = unsigned int;
using i64 = long long;
using u64 = unsigned long long;
using i128 = __int128_t;
using u128 = __uint128_t;
using f64 = long double;
using p2 = pair<i64, i64>;
using el = tuple<i64, i64, i64>;
using mint = atcoder::modint998244353;

void _main();
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(3);
  _main();
}

i32 pow(i32 x, i32 n) {
  i32 res = 1;
  i32 a = x;
  while (n > 0) {
    if (n & 1) res *= a;
    a *= a;
    n >>= 1;
  }
  return res;
}

void _main() {
  i64 t;
  cin >> t;
  for (;t--;) {
    i64 n;
    cin >> n;
    vector<i64> a(n);
    bool zero = false;
    for (i64 i = 0; i < n; i++) {
      cin >> a[i];
      if (a[i] == 0) zero = true;
    }
    sort(a.begin(), a.end());
    if (zero) {
      cout << "0\n";
      continue;
    }
    if (a[0] < 0 && a[n - 1] > 0) {
      i64 x = -1e18, y = 1e18;
      for (i64 i = 0; i < n; i++) {
        if (a[i] < 0) x = max(x, a[i]);
        else y = min(y, a[i]);
      }
      cout << x * y << "\n";
      continue;
    }
    if (a[0] < 0) {
      for (i64 i = 0; i < n; i++) {
        a[i] = -a[i];
      }
      reverse(a.begin(), a.end());
    }
    cout << a[0] * a[n - 1] << "\n";
  }
}