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 argc, char const *argv[]) {
  int t;
  cin >> t;
  while (t--) {
    int n;
    cin >> n;
    int arr[n];
    int a = 0;
    for (int i = 0; i < n; i++) {
      cin >> arr[i];
    }
    int max = 0;
    for (int i = 0; i < n; i++) {
      if (arr[i] > max) {
        max = arr[i];
      }
    }
    for (int i = 0; i < n - 1; i++) {
      if (arr[i] == arr[i + 1]) a++;
    }
    if (a == n - 1) {
      cout << "-1\n";
    } else {
      for (int i = 0; i < n; i++) {
        if (arr[i] == max) {
          if (i - 1 > 0 && arr[i] != arr[i - 1]) {
            cout << i + 1 << '\n';
            break;
          } else if (i + 1 < n && arr[i] != arr[i + 1]) {
            cout << i + 1 << '\n';
            break;
          }
        }
      }
    }
  }
  return 0;
}
