#define _USE_MATH_DEFINES
#include<stdio.h>
#include<string>
#include<iostream>
#include<cctype>
#include<cstdio>
#include<vector>
#include<stack>
#include <algorithm>
#include<math.h>
#include<set>
#include<map>
#include<iomanip>
//#include<bits/stdc++.h>


using namespace std;




int main() {
  
	long long int a,b,n;
	cin>>a>>b>>n;
	long long int p=a^b;
	if(n%3==2)cout<<p<<endl;
	if(n%3==1)cout<<b<<endl;
	if(n%3==0)cout<<a<<endl;
    return 0;
}