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 sc = new Scanner(System.in);
    int t = sc.nextInt();
    while(t-->0){
        int n = sc.nextInt();
        int a[] = new int[n];
       // Stack<Integer> s = new Stack<>();
       int mx = 0;
       int k =0;
        for(int i=0;i<n;i++){
            a[i] = sc.nextInt();
           mx =  Math.max(mx,a[i]);
           k=i;
        }
       // System.out.println(mx+"  "+k);
        int idx = -1;
        for(int i=0;i<n;i++){
            if(a[i]!=mx)continue;
            if(i>0&&a[i-1]!=mx)
            idx = i+1;
            if(i<n-1&&a[i+1]!=mx)
            idx = i+1;
        }
        System.out.println(idx);}}}