1 import java.util.*;
 2 public class Main {
 3     public static void main(String[] args) {
 4         Scanner sc = new Scanner(System.in);
 5         int n = sc.nextInt();
 6         int[] a = new int[n];
 7         for(int i=0;i<n;i++)
 8             a[i] = sc.nextInt();
 9         int s = sc.nextInt();
10         boolean b = true;
11         for(int i=0;i<n;i++)
12             if(a[i]==s){
13                 b = false;
14                 System.out.println(i+1);
15                 break;
16             }
17         if(b)
18             System.out.println(-1);
19     }
20 }