#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<cmath>
#include<stdio.h>
#include<queue>
#include <climits>
#include <map>
#include <set>
const int mod = 1e9 + 7;
const long long INF = 1LL << 60;
using namespace std;
typedef long long ll;

int main()
{
    ll a,b,n;
    cin >> a >> b >> n;
    if(n == 0) {
        cout << a << endl;
        return 0;
    }
    if(n == 1) {
        cout << b << endl;
        return 0;
    }
    else{
        for(int i = 0; i < n-1; i++){
            ll tmp = a ^ b;
            a = b;
            b = tmp;
        }
        cout << b << endl;
        return 0;
    }
}