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() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int t = 1;
  cin >> t;
  while (t--) {
    int n;
    cin >> n;
    int a[n];
    for (int i = 0; i < n; i++) cin >> a[i];
    int max = a[0];
    for (int i = 1; i < n; i++)
      if (a[i] > max) max = a[i];
    for (int i = 0; i < n; i++) {
      if (max == a[i]) {
        if (i != 0)
          cout << i + 1 << endl;
        else {
          for (i += 1; i < n; i++)
            if (a[i] != max) {
              cout << i << endl;
              break;
            }
          if (i == n) cout << "-1" << endl;
        }
        break;
      }
    }
  }
  return 0;
}
