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 r = 0;
        
        if(B>A){
            r=B-2;
        }else{
            r=2000000000-B-1;
        }
        System.out.println(r);
    }
}