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 x = 1L;
        var imax = 0;
        var abmax = Max(a, b);
        for (int i = 0; i < 31; i++)
        {
            if (x >= abmax) { imax = i; break; }
            x *= 2;
        }
        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)) { Console.WriteLine("i = {0}", i); count++; }
        }
        if (count <= 1) Console.WriteLine(1);
        else Console.WriteLine(Pow(2, count - 1));
    }
}