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--) {
    int n;
    cin >> n;
    vector<int> v(n);
    for (int i = 0; i < n; i++) {
      cin >> v[i];
    }
    int f = 0;
    for (int i = 1; i < n; i++) {
      if (v[i] != v[i - 1]) {
        f = 1;
      }
    }
    if (f == 0) {
      cout << "-1" << endl;
    } else {
      int mx = INT_MIN;
      int index = -1;
      for (int i = 0; i < n; i++) {
        if (mx <= v[i]) {
          mx = v[i];
          index = i;
        } else {
          break;
        }
      }
      for (int i = 0; i < n; i++) {
        if (mx < v[i]) {
          mx = v[i];
          index = i;
        }
      }
      cout << index + 1 << endl;
    }
  }
  return 0;
}
