import java.util.*;
public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int m = sc.nextInt();
		int x = sc.nextInt();
		int [] a = new int [m];
		int right = 0;
		int left = 0;
		for(int i = 0; i < m; i++) {
			a[i] = sc.nextInt();
		}
		for(int i = 1; i < x; i++) {
			for(int j = 0; j < m; j++) {
				if(i == a[j]) {
					left++;
				}
			}
		}
		for(int i = x+1; i < n; i++) {
			for(int j = 0; j < m; j++) {
				if(i == a[j]) {
					right++;
				}
			}
		}
		if(left <= right) {
			System.out.println(left);
		}
		else {
			System.out.println(right);
		}
		sc.close();
	}

}

/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz