package yukicorder;

import java.util.Scanner;

public class No333 {
	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int a = sc.nextInt();
		int b = sc.nextInt();

		int c = 0;

		if(b>a){
			c = b - 2;
		}else if(a>b){
			c = 2000000000 - b - 1;
		}
		System.out.println(c);
	}
}