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

class Program
{
    static void Main()
    {
        long[] n = Console.ReadLine().Split().Select(a => long.Parse(a)).ToArray();
        if(n[2] % 3 == 0)
        {
            Console.WriteLine($"{n[0]}");
        }
        else if(n[2] % 3 == 1)
        {
            Console.WriteLine($"{n[1]}");
        }
        else
        {
            Console.WriteLine($"{n[0] ^ n[1]}");
        }
    }
}