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();
        long l = n[2] + 1;
        if(l < 2)
            l = 2;
        long[] list = new long[l];
        list[0] = n[0];
        list[1] = n[1];
        for(long i = 2; i < l; i++)
        {
            list[i] = list[i - 2] ^ list[i - 1];
        }
        Console.WriteLine($"{list[n[2]]}");
    }
}