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

class AOJ {
    static void Main() {
        long[] a = Console.ReadLine().Split().Select(long.Parse).ToArray();
        long[] f = new long[3];
        f[0] = a[0];
        f[1] = a[1];
        f[2] = a[0] ^ a[1];
        Console.WriteLine(f[a[2] % 3]);
    }
}