#include <bits/stdc++.h>
using namespace std;
const long long mod = 1e9 + 7;
long long find(long long a[], long long n) {
  if (n < 5) return -1;
  sort(a, a + n);
  long long last = a[n - 1] * a[n - 2] * a[n - 3] * a[n - 4] * a[n - 5];
  long long first = a[0] * a[1] * a[2] * a[3] * a[4];
  long long two = a[0] * a[1] * a[n - 1] * a[n - 2];
  if (two * a[2] > (two * a[n - 3]))
    two *= a[2];
  else
    two = a[n - 3];
  return max(last, max(first, two));
}
int main() {
  long long t;
  cin >> t;
  while (t--) {
    long long n;
    cin >> n;
    long long a[n], i;
    for (i = 0; i < n; i++) cin >> a[i];
    sort(a, a + n);
    long long last = a[n - 1] * a[n - 2] * a[n - 3] * a[n - 4] * a[n - 5];
    long long first = a[0] * a[1] * a[2] * a[3] * a[4];
    long long two = a[0] * a[1] * a[n - 1] * a[n - 2];
    if ((two * a[2]) > (two * a[n - 3]))
      two *= a[2];
    else
      two *= a[n - 3];
    long long four = max(a[0] * a[n - 1] * a[n - 2] * a[n - 3] * a[n - 4],
                         a[0] * a[1] * a[2] * a[3] * a[n - 1]);
    cout << max({last, first, two, four}) << "\n";
  }
  return 0;
}
