#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
  #define _GLIBCXX_DEBUG
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  ll a, b, c;
  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;
}