#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <utility>

using namespace std;

const long long pattern[4][3] = {
	{0, 0, 0},
	{0, 1, 1},
	{1, 0, 1},
	{1, 1, 0}
};

int main() {
	long long f0, f1, n;

	cin >> f0 >> f1 >> n;

	n %= 3;
	int bit0, bit1;
	long long ans = 0;

	for (int i = 0; i < 60; i++) {
		bit0 = (f0 >> i) & 1;
		bit1 = (f1 >> i) & 1;

		ans |= pattern[(bit0 << 1) | bit1][n] << i;
	}

	cout << ans << endl;
	return 0;
}