#define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES
#include <iostream>
#include <map>
#include <list>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <string>
#include <vector>
#include <algorithm>
#include <utility>
#include <queue>
#include <iomanip>
#define INF 1050000000

using namespace std;


int main(void)
{
	long long f[3], n;
	long long ans;

	cin >> f[0] >> f[1] >> n;

	f[2] = f[0] ^ f[1];

	cout << f[n % 3] << endl;

	 return (0);
}