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 a;
    cin >> a;
    int arr[a];
    set<int> s;
    int max = 0;
    for (int i = 0; i < a; i++) {
      cin >> arr[i];
      if (arr[i] > max) {
        max = arr[i];
      }
      s.insert(arr[i]);
    }
    if (s.size() == 1)
      cout << "-1" << endl;
    else {
      for (int i = 0; i < a; i++) {
        if (arr[i] == max) {
          if (i == 0 and arr[i + 1] != arr[i]) {
            cout << "1" << endl;
            break;
          } else if (i == a - 1 and arr[i] != arr[i - 1]) {
            cout << a << endl;
            break;
          } else if ((arr[i] != arr[i - 1] || arr[i] != arr[i + 1]) and
                     i != 0 and i != a - 1) {
            cout << i + 1 << endl;
            break;
          }
        }
      }
    }
  }
}
