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_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int n;
  cin >> n;
  for (int i = 0; i < n; i++) {
    int size;
    cin >> size;
    int max = 0;
    double avg;
    int sum = 0;
    int pos = -1;
    int *arr = new int[size];
    for (int i = 0; i < size; i++) {
      cin >> arr[i];
      sum += arr[i];
      if (arr[i] > max) max = arr[i];
    }
    avg = sum / size;
    for (int i = 0; i < size; i++) {
      if ((arr[i] == max) && (arr[i] > avg)) {
        pos = i + 1;
        break;
      }
    }
    cout << pos << endl;
  }
  return 0;
}
