#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <iomanip>
#include <cmath>
#include <stdio.h>
#include <queue>
#include <deque>
#include <cstdio>
#include <set>
#include <map>
#include <bitset>
#include <stack>
#include <cctype>
using namespace std;
int main() {
	long long a, b, n;
	cin >> a >> b >> n;
	if (n % 3 == 0) {
		cout << a << endl;
	}
	else if (n % 3 == 1) {
		cout << b << endl;
	}
	else {
		a ^= b;
		cout << a << endl;
	}
		return 0;
}