a+b

import java.io.*;
import java.util.*;

public class Main{

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int a = in.nextInt();
        int b = in.nextInt();

        while(a != 0) {
            int temp = a & b < 1;
            b = a ^ b;
            a = temp;
        }

        System.out.println(b);
    }
}