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, max = 0, c = 0;
    cin >> n;
    int arr[n];
    vector<int> v;
    for (int i = 0; i < n; i++) {
      cin >> arr[i];
      v.push_back(arr[i]);
    }
    sort(v.begin(), v.end());
    max = v[v.size() - 1];
    if (arr[0] == max && arr[1] < arr[0])
      cout << "1" << endl;
    else if (arr[n - 1] == max && arr[n - 2] < arr[n - 1])
      cout << n << endl;
    else {
      for (int i = 1; i < n - 1; i++) {
        if (max == arr[i] && arr[i - 1] < arr[i] && arr[i + 1] < arr[i]) {
          cout << i + 1 << endl;
          break;
        } else
          c++;
      }
      if (c == n - 2) cout << "-1" << endl;
    }
  }
  return 0;
}
