import java.util.Scanner;

public class Test {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int a = sc.nextInt(), b = sc.nextInt(), c = 2000000000;
		if (a < b) {
			System.out.println(b - 2);
		} else {
			System.out.println(c - b - 1);
		}
	}
}