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

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int a = sc.nextInt();
        int b = sc.nextInt();
        long ans = 1;
        while (a > 0 || b > 0) {
            if (b % 2 == 0) {
                if (a % 2 == 1) {
                    System.out.println(0);
                    return;
                }
            } else {
                if (a % 2 == 0) {
                    ans <<= 1;
                }
            }
            a >>= 1;
            b >>= 1;
        }
        if (ans == 1) {
            ans = 2;
        }
        System.out.println(ans / 2);
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
    
}