import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt(), m = in.nextInt(), x = in.nextInt();
        int[] a = new int[n];
        for (int i = 0; i < m; i++) {
            a[in.nextInt()] = 1;
        }
        int ans1 = 0,ans2 = 0;
        for (int i = x; i > 0; i--) {
            ans1 += a[i];
        }
        for (int i = x; i < n; i++) {
            ans2 += a[i];
        }
        System.out.println(Math.min(ans1, ans2));
    }
}

/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