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 a[1000005];
int main(int argc, char** argv) {
  int T;
  cin >> T;
  while (T--) {
    int n;
    cin >> n;
    for (int i = 1; i <= n; i++) cin >> a[i];
    int mx = 0;
    for (int i = 1; i <= n; i++) mx = max(mx, a[i]);
    int flag = 1;
    for (int i = 1; i < n; i++) {
      if (a[i] == mx && a[i + 1] != mx) {
        cout << i << "\n";
        flag = 0;
        break;
      }
    }
    if (flag)
      for (int i = 2; i <= n; i++) {
        if (a[i] == mx && a[i - 1] != mx) {
          cout << i << "\n";
          flag = 0;
          break;
        }
      }
    if (flag) puts("-1");
  }
  return 0;
}
