import java.util.*;
public class xiaowuc1 {
  public static void main(String[] args) throws Exception {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    int[] bad = new int[n];
    int x = sc.nextInt(); x--;
    int q = sc.nextInt();
    for(int i = 0; i < q; i++) bad[sc.nextInt()-1]++;
    int rhs = 0;
    for(int i = 0; i < x; i++) rhs += bad[i];
    System.out.println(Math.min(rhs, q - rhs));
  }
}