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

class Main {
	public static void main(String[] args) {
		new Main().run();
	}
    
    void run() {
        Scanner sc = new Scanner(System.in);
        long A = sc.nextLong();
        long B = sc.nextLong();
        long ans=1;
        for (long i=0;i<31;++i){
            long u=(A>>i)%2;
            long v=(B>>i)%2;
            if(u==1&&v==0)ans=0;
            else if(u==0&&v==1)ans=ans*2;
            else if(u==1&&v==1)ans=ans;
            else if(u==0&&v==0)ans=ans;
        }
        if(ans==1)System.out.println(ans);
        else System.out.println(ans/2);
    }
}