#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

int solve(int f0, int f1, ll N) {
	if (f0 == 0 && f1 == 0) {
		return 0;
	}
	int idx = 0;
	if (f0 == 0 && f1 == 1) {
		idx = 2;
	}
	else if (f0 == 1 && f1 == 0) {
		idx = 1;
	}
	int a = (N + idx) % 3;
	return a == 2 ? 0 : 1;
}

int main() {
	ll f0, f1, N; cin >> f0 >> f1 >> N;
	ll f = 0;
	for (int i = 0; (1LL << i) <= max(f0, f1); ++i) {
		int a = (f0 & (1LL << i)) ? 1 : 0;
		int b = (f1 & (1LL << i)) ? 1 : 0;
		f |= (ll)solve(a, b, N) << i;
	}
	cout << f << endl;
}