#include<iostream>
#include<cmath>
#include<cstdio>
using namespace std;

int main()
{
    long long int x, y, n;
    long long int ans[3];

    cin >> x >> y >> n;
    ans[0] = x;
    ans[1] = y;
    ans[2] = x ^ y;
    cout << ans[n%3] << endl;

    return 0;
}