#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <iomanip>
#include <functional>
#include <cmath>
using namespace std;
#define lli long long int
#define MAX 1000
lli dp[MAX];

lli fib(lli n) {
	//cout << n << " " << dp[n] << endl;
	if (dp[n] > -1)
		return dp[n];
	else
		return dp[n] = fib(n - 1) ^ fib(n - 2);
}

int main() {
	for (int i = 0; i < MAX; i++)
		dp[i] = -5;
	lli n, x;
	cin >> dp[0] >> dp[1] >> n;
	cout << fib(n) << endl;
	return 0;
}