#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using PII = std::pair<int, int>;
using PLL = std::pair<ll, ll>;

#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep2(i, s, n) for (int i = (s); i < (int)(n); i++)



int main()
{

#ifdef DEBUG
    cout << "DEBUG MODE" << endl;
    ifstream in("input.txt"); //for debug
    cin.rdbuf(in.rdbuf());    //for debug
#endif

    ll a, b, n;
    cin >> a >> b >> n;
    if (n % 3 == 0)
        cout << a << endl;
    else if (n % 3 == 1)
        cout << b << endl;
    else if (n % 3 == 2)
        cout << (a ^ b) << endl;
    
    return 0;
}