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(false);
  cin.tie(0);
  cout.tie(0);
  int t;
  cin >> t;
  while (t--) {
    long long int n, i, j;
    cin >> n;
    long long int a[n], e = 0, f = INT_MAX;
    for (i = 0; i < n; i++) {
      cin >> a[i];
      f = min(f, a[i]);
    }
    if (f == a[n - 1] && a[n - 1] != a[n - 2]) {
      cout << n << endl;
      continue;
    }
    for (i = 0; i < n - 1; i++) {
      if (f == a[i] && a[i] != a[i + 1]) {
        cout << i + 1 << endl;
        e = 1;
        break;
      }
    }
    if (e == 0) cout << -1 << endl;
  }
}
