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

import java.util.*;
public class Main {
    public static void main(String args[]) {
        Scanner s = new Scanner(System.in);
        int t = s.nextInt();
        while(t-- != 0){
            int n = s.nextInt();
            int arr[] = new int[n];
            int max = Integer.MIN_VALUE;
            for(int i = 0; i < n; i++){
                arr[i] = s.nextInt();
                max = Math.max(max,arr[i]);
            }
            int ans = -1;
            for(int i = 0; i < n - 1; i++){
                if(arr[i] != max){
                    continue;
                }
                if((i > 0 && arr[i - 1] < max) || (i < n - 1 && arr[i + 1] < max)){
                    ans = i + 1;
                }
            }
            System.out.println(ans);   
        }
    }
}