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(0);
  cin.tie(0);
  cout.tie(0);
  int t;
  cin >> t;
  while (t--) {
    int n;
    cin >> n;
    int a[n];
    map<int, int> m;
    int mx = INT_MIN;
    int pos = 0;
    for (int i = 0; i < n; i++) {
      cin >> a[i];
      m[a[i]]++;
      if (a[i] > mx) {
        mx = a[i];
        pos = i + 1;
      }
    }
    if (m.size() == 1) {
      cout << "-1"
           << "\n";
    } else {
      cout << pos << "\n";
    }
  }
}
