#include<bits/stdc++.h>
using namespace std;
typedef pair<int, int> pii;
typedef long long int ll;

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    
    ll a, b, c, n;
    cin >> a >> b >> n;
    if (n == 0)
        cout << a << endl;
    else if (n == 1)
        cout << b << endl;
    else {
        for (int i = 2; i <= n; i++) {
            c = a ^ b;
            a = b;
            b = c;
        }
        cout << c << endl;
    }

}