#pragma GCC optimize("Ofast")
#include<iostream>
#include<stdio.h>
#include<algorithm>
#include<vector>
#include<string.h>
#include<math.h>
#include<map>
#include<iomanip>
#include<queue>

const long long INFL = 1e17+7;
const long long INFI = 1e9+7;
const long long MOD = 1e9+7;
const double EXP = 1e-8;
const double PI=acos(-1);

using namespace std;

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);
	
	int f1,f2,n;
	cin >> f1 >> f2 >> n;
	vector<int> a;
	a.push_back(f1);
	a.push_back(f2);
	a.push_back(f1 xor f2);
	cout << a[n%3] << endl;
	return 0;
}