import java.util.*;
public class Main {
static int binarySearch(int[] arr,int data) {
int low = 0;
int high = arr.length - 1;
while (low <= high) {
int mid = (low + high) / 2;
if(data>arr[mid]) {
low=mid+1;
}
else if(data<arr[mid]) {
high=low-1;
}
else {
return mid;
}
}
return -1;
}
public static void main(String args[]) {
Scanner sc = new Scanner(System.in);
int size = sc.nextInt();
int[] arr = new int[size];
for (int i = 0; i < arr.length; i++) {
arr[i] = sc.nextInt();
}
int data = sc.nextInt();
int result = binarySearch(arr,data);
if (result > 0)
System.out.println(result);
}
}