#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
#define ll long long
#define rep(i, n) for (int i = 0; i < (n); i++)
#define coutf(f) cout << fixed << setprecision(f)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()

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