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 std::cin;
using std::cout;
int n, max, myIndex;
void Solve() {
  cin >> n;
  int arr[n];
  max = 0;
  myIndex = 0;
  for (auto &it : arr) {
    cin >> it;
    if (it > max) max = it;
  }
  for (int i = 0; i < n; i++) {
    if (arr[i] != max) continue;
    if (arr[i - 1] != max) myIndex = i + 1;
    if (arr[i + 1] != max) myIndex = i + 1;
  }
  cout << myIndex << '\n';
}
int main() {
  int t;
  cin >> t;
  while (t--) {
    Solve();
  }
}
