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

namespace YukiCoder
{
    class Program
    {
        static void Main(string[] args)
        {
            var va = Console.ReadLine().Split().Select(long.Parse).ToArray();
            long nn = va[2] % 3;
            va[2] = va[0] ^ va[1];
            Console.WriteLine(va[nn]);
            Console.ReadLine();
        }
    }
}