import java.util.Scanner;

public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner scanner=new Scanner(System.in);
        int N=scanner.nextInt();
        int M=scanner.nextInt();
        int X=scanner.nextInt();
        boolean booleans[]=new boolean[N+1];
        for(int i=0;i<=N;i++){
            booleans[i]=false;
        }
        for(int i=0;i<M;i++){
            booleans[scanner.nextInt()]=true;
        }
        int a=0;
        int b=0;
        for(int i=1;i<X;i++){
            if(booleans[i]) a++;
        }
        for(int i=X+1;i<N;i++){
            if(booleans[i]) b++;
        }
        System.out.println(Math.min(a,b));
    }
}

/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