using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

class Magatro
{
    static void Main()
    {
        long[] N = Console.ReadLine().Split(' ').Select(s => long.Parse(s)).ToArray();
        if (N[2] % 3 == 0)
        {
            Console.WriteLine(N[0]);
        }
        else if (N[2] % 3 == 1)
        {
            Console.WriteLine(N[1]);
        }
        else
        {
            string a = Convert.ToString(N[0], 2);
            string b = Convert.ToString(N[1], 2);
            int l = Math.Max(a.Length, b.Length);
            string f = string.Format("0:D{0}", l);
            a = string.Format("{"+ f+"}", a);
            b = string.Format("{"+f+"}", b);
            string c = "";
            for(int i = 0; i < l; i++)
            {
                if (a[i] == '1' ^ b[i] == '1')
                {
                    c += "1";
                }
                else
                {
                    c += "0";
                }
            }
            Console.Write(Convert.ToInt64(c,2));
        }

       

    }

}