#include <iostream>
#include <fstream>
#include <vector>
#include <string>
#include <algorithm>
//---------------------------
using namespace std;
//---------------------------
#define REP(i,n) for(int i = 0; i < (n); i++)
#define P(x) cout << (x) << "\n"
//---------------------------


int main(){
  std::ios::sync_with_stdio(false);
  std::cin.tie(0);



  long long N;
  vector<long long> a(N+1),b(N+1),c(N+1);
  cin >> a[0] >> b[1] >> N;
  long long ans;
  if (N == 0) {
    ans = a[0];
  }else{
  REP(i,N-1){
    c[i+2] = b[i+1] ^ a[i];
    //次のiに値を渡す
    a[i+1] = b[i+1];
    b[i+2] = c[i+2];
  }
  ans = c[N];
}
  P(ans);
  return 0;
}