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, d = 0, i, j, f = 0;
    cin >> n;
    int arr[n + 2];
    pair<int, int> ara[n];
    for (i = 1; i <= n; i++) {
      cin >> arr[i];
      ara[i - 1].first = arr[i];
      ara[i - 1].second = i - 1;
    }
    arr[0] = 1000000001;
    arr[n + 1] = 1000000001;
    sort(ara, ara + n);
    for (i = n - 1; i >= 0; i--) {
      d = ara[i].second;
      if ((ara[i].first > arr[d]) || (ara[i].first > arr[d + 2])) {
        cout << (ara[i].second + 1) << endl;
        f = 1;
        break;
      }
    }
    if (f == 0) {
      cout << "-1\n";
    }
  }
  return 0;
}
