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--) {
    long long int n;
    cin >> n;
    long long int arr[n];
    long long int max = 0;
    long long int idx;
    for (int i = 0; i < n; i++) {
      cin >> arr[i];
      if (arr[i] > max) {
        max = arr[i];
        idx = i;
      }
    }
    bool flag = false;
    for (int i = 0; i < n; i++) {
      if (arr[i] != max) {
        flag = true;
      }
    }
    if (flag) {
      cout << idx + 1 << "\n";
    } else {
      cout << -1 << "\n";
    }
  }
  return 0;
}
