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 asd
{
         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+2];
                    arr[0]=Integer.MAX_VALUE;
                    arr[n+1]=Integer.MAX_VALUE;
                    int count=0;
                    
                    int index=-1;
                    for(int i=01;i<=n;i++)
                    {
                        arr[i]=s.nextInt();
                    }
                    int max=arr[1];
                    for(int i=01;i<=n;i++)
                    {
                        if(arr[i]>=max)
                        {    max=arr[i];
                        if(arr[i+1]<arr[i])
                            index=i;
                        else if (arr[i-1]<arr[i])
                            index=i;
                        }
                    }
                    System.out.println(index);
                   
                   
                }
                
               

          }
}
             

       


         
         
