#include <cstdio>
#include <iostream>
#include <string>
#include <vector>
#include <sstream>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <cmath>
#include <cstdlib>
#include <cstring>
#include <typeinfo>
#include <numeric>
#include <functional>
#include <unordered_map>
#include <bitset>


using namespace std;
using ll = long long;
using ull = unsigned long long;

const ll INF = 1e16;
const ll MOD = 1e9 + 7;

#define REP(i, n) for(ll i = 0; i < n; i++)




int main() {
    ll f0, f1, n;
    cin >> f0 >> f1 >> n;
    
    if(n == 0){
        cout << f0 << endl;
        return 0;
    }
    if(n == 1){
        cout << f1 << endl;
        return 0;
    }
    if(n == 2){
        cout << (f0 xor f1) << endl;
        return 0;
    }
    
    ll ans = 0;
    REP(i, 64){
        ll b1 = (f0 >> i) & 1, b2 = (f1 >> i) & 1;
        
        // cout << b1 << ' ' << b2 << endl;
        
        if(!b1 && b2){
            if(n % 3 != 0){
                ans |= (1LL << i);
            }
        }
        else if(b1 && !b2){
            if(n % 3 != 1){
                ans |= (1LL << i);
            }
        }
        else if(b1 && b2){
            if(n % 3 != 2){
                ans |= (1LL << i);
            }
        }
        
        // cout << ans << endl;
    }
    
    cout << ans << endl;
}