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