using static System.Math;
using System;

public class Hello
{
    public static long a, b;
    static void Main()
    {
        string[] line = Console.ReadLine().Trim().Split(' ');
        a = long.Parse(line[0]);
        b = long.Parse(line[1]);
        getAns();
    }
    static bool check(long t, int p) => ((t >> p) & 1) == 1;
    static void getAns()
    {
        var imax = countBIT(Max(a, b));
        var count = 0;
        for (int i = 0; i < imax; i++)
        {
            if (check(a, i) && !check(b, i)) { Console.WriteLine(0); return; }
            if (!check(a, i) && check(b, i)) count++;
        }
        Console.WriteLine(Pow(2, count - 1));
    }
    static int countBIT(long bits)
    {
        bits = (bits & 0x55555555) + (bits >> 1 & 0x55555555);
        bits = (bits & 0x33333333) + (bits >> 2 & 0x33333333);
        bits = (bits & 0x0f0f0f0f) + (bits >> 4 & 0x0f0f0f0f);
        bits = (bits & 0x00ff00ff) + (bits >> 8 & 0x00ff00ff);
        return (int)(bits & 0x0000ffff) + (int)(bits >> 16 & 0x0000ffff);
    }
}