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
        {
            long ans = N[1] ^ N[0];
            Console.WriteLine(ans);
        }

       

    }

}