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 in = new Scanner(System.in);
        int t  = in.nextInt();
        while(t-->0)
        {
           int n = in.nextInt();
           int a[] = new int[n];
           int max=-1 , flag=0,pos=-1;
           for(int i=0 ; i<n ; i++)
           {
               a[i] = in.nextInt();
               if(i>0&&a[i]!=a[i-1]&&a[i]>max) {
                   max=a[i];
                   pos=i+1;
                   flag=1;
               }
           }
           if(flag==1) System.out.println(pos);
           else System.out.println("-1");
        }
    }
}