using System;

class Program
{
    static void Main(string[] args)
    {
        var line = Console.ReadLine().Split(' ');
        var binA = long.Parse(Convert.ToString(int.Parse(line[0]), 2));
        var binC = long.Parse(Convert.ToString(int.Parse(line[1]), 2));
        var binB = (binA ^ binC).ToString();
        Console.WriteLine(Convert.ToInt32(binB, 2));
    }
}