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;
  scanf("%d", &t);
  while (t--) {
    int n;
    cin >> n;
    int a[n];
    for (int i = 0; i < n; i++) cin >> a[i];
    int m = *max_element(a, a + n);
    int ans = -1;
    for (int i = 0; i < n; i++) {
      if (a[i] == m) {
        if ((i - 1 >= 0 && a[i - 1] != a[i]) ||
            (i + 1 < n && a[i + 1] != a[i])) {
          ans = i + 1;
          break;
        }
      }
    }
    cout << ans << endl;
  }
  return 0;
}
