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--) {
    int n, m = -1, f = 0, ind = 0;
    cin >> n;
    vector<int> a(n);
    for (int i = 0; i < n; i++) {
      cin >> a[i];
      if (a[i] > m) {
        m = a[i];
        ind = i;
      }
      if (i > 0 && a[i] != a[i - 1]) f = 1;
    }
    if (f == 0)
      cout << "-1\n";
    else {
      for (int i = 0; i < n; i++) {
        if (i > 0 && a[i] == m && a[i - 1] != m) {
          ind = i + 1;
          break;
        }
        if (i < n - 1 && a[i] == m && a[i + 1] != m) {
          ind = i + 1;
          break;
        }
      }
      cout << ind << "\n";
    }
  }
  return 0;
}
