#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <iomanip>
#include <functional>
#include <cmath>
using namespace std;
#define lli long long int

int main() {
	lli a, b, n;
	cin >> a >> b >> n;
	if (n % 3 == 0)			cout << a << endl;
	else if (n % 3 == 1)	cout << b << endl;
	else					cout << (a ^ b) << endl;
	return 0;
}