#include <cstdio>
#include <cstdlib>
#include <cstddef>
#include <vector>
#include <algorithm>
#include <cmath>
#include <string>
#include <iostream>
#include <iomanip>

int main(void)
{
	long f0, f1, n;
	std::cin >> f0 >> f1 >> n;
    std::vector<long> v0, v1;
    while(0 < f0){
        v0.push_back(f0 % 2);
        f0 /= 2;
    }
    while(0 < f1){
        v1.push_back(f1 % 2);
        f1 /= 2;
    }
    if(v0.size() < v1.size()){
        for(long i = v0.size(); i < (long)v1.size(); i++){
            v0.push_back(0);
        }
    } else if(v1.size() < v0.size()){
        for(long i = v1.size(); i < (long)v0.size(); i++){
            v1.push_back(0);
        }
    }
    long sz = v1.size();
    long res = 0;
    for(long i = 0; i < sz; i++){
        // 1, 0, 1, 1, 0, ...
        // 0, 0, 0, ...
        long b0 = v0[i];
        long b1 = v1[i];
        if(b0  == 0){
            if(b1 == 1){
                if(n % 3 != 0){
                    res += 1 << i;
                }
            }
        } else {
            if(b1 == 0){
                if(n % 3 != 1){
                    res += 1 << i;
                }
            } else {
                if(n % 3 != 2){
                    res += 1 << i;
                }
            }
        }
    }
    std::cout << res << std::endl;
	return 0;
}