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);
  long long int t;
  cin >> t;
  while (t--) {
    long long int r;
    cin >> r;
    long long int A[r];
    int ind;
    long long int large = -1, flag = 1;
    for (long long int i = 0; i < r; i++) cin >> A[i];
    for (long long int i = 0; i < r; i++) {
      if (A[i] > large) {
        large = A[i];
        flag = 1;
        ind = i + 1;
      } else if (A[i] == large) {
        flag++;
        if (A[i + 1] < A[i] || A[i - 1] < A[i]) ind = i + 1;
      }
    }
    if (flag == r)
      cout << "-1\n";
    else
      cout << ind << "\n";
  }
  return 0;
}
