1
3
5 3 4
 6
5
5 3 4 4 5
3
1 1 1
5
4 4 3 4 4
5
5 5 4 3 2
3
1 1 2
5
5 4 3 5 5
 1
3
10 1 5

1
 1
-1
2
2
3
1
 1

#include <bits/stdc++.h>
using namespace std;
int main() {
  int t;
  cin >> t;
  while (t != 0) {
    int n, x = 0;
    cin >> n;
    int i, a[n];
    for (i = 0; i < n; i++) {
      cin >> a[i];
    }
    int p = a[1];
    for (i = 0; i < n; i++) {
      if (a[i] > x) {
        x = a[i];
      }
      if (a[i] < p) {
        p = a[i];
      }
    }
    if (p == x) {
      x = -1;
    }
    cout << x << "\n";
    t = t - 1;
  }
  return 0;
}
