import java.util.*;
public class Main{
    public static void main(String[]args){
        Scanner scn=new Scanner(System.in);
        int n=scn.nextInt();
        if(n<=0){
            System.out.print("Invalid input");
            return;
        }
        int []arr=new int[n];
        for(int i=0;i<n;i++){
            arr[i]=scn.nextInt();
        }
        int target=scn.nextInt();
        for(int i=0;i<n;i++){
                if(target==arr[i]){
                    System.out.println(i);
                }
                else if(targer!=arr[i]){
                                        System.out.println(-1);

                }
            
        }
    }
}