#include <bits/stdc++.h>
using namespace std;
long long a, b, c;
int main() {
	cin >> a >> b >> c;
	if(c % 3 == 0) cout << a << endl;
	if(c % 3 == 1) cout << b << endl;
	if(c % 3 == 2) cout << (a ^ b) << endl;
	return 0;
}