using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;
using System.Runtime.Intrinsics.Arm;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static string[] SList(long n) => Enumerable.Repeat(0, (int)n).Select(_ => ReadLine()).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var c = NList;
        if (c[0] == c[1])
        {
            WriteLine(1);
            return;
        }
        if (((c[0] & c[1]) != c[0]) || ((c[0] | c[1]) != c[1]))
        {
            WriteLine(0);
            return;
        }
        var ans = 1;
        for (var i = 0; i < 31; ++i) if (((c[0] >> i) & 1) != ((c[1] >> i) & 1)) ans <<= 1;
        WriteLine(ans >> 1);
    }
}