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::sync_with_stdio(0);
  cin.tie(0);
  int t;
  cin >> t;
  while (t--) {
    int n;
    cin >> n;
    int arr[n];
    int max = 0;
    bool flag = false;
    for (int i = 0; i < n; i++) {
      cin >> arr[i];
      if (arr[max] < arr[i]) max = i;
      if (i >= 1) {
        if (arr[i] != arr[i - 1]) flag = true;
      }
    }
    if (flag) {
      cout << max + 1;
    } else
      cout << -1;
    cout << endl;
  }
}
