import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int a = sc.nextInt();
    int b = sc.nextInt();
    int ans = 0;
    if(a > b) ans = (int)Math.pow(10, 9) * 2 - b - 1;
    if(a < b) ans = b - 2;
    System.out.println(ans);
  }
}