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 q;
  cin >> q;
  while (q--) {
    int n;
    cin >> n;
    long long arr[n];
    for (int i = 0; i < n; i++) {
      cin >> arr[i];
    }
    int ans = -1;
    for (int i = 0; i < n - 1; i++) {
      if (arr[i] != arr[i + 1]) {
        ans = 1;
      }
    }
    if (ans == 1) {
      long long mx = 0;
      int ind = 0;
      for (int i = 0; i < n; i++) {
        if (arr[i] > mx) {
          mx = arr[i];
          ind = i;
        }
      }
      cout << ++ind << endl;
    } else {
      cout << -1 << endl;
    }
  }
  return 0;
}
