#include <iostream>
#include <math.h>
#include <string>
#include <algorithm>

typedef long long ll;
#define MIN(x, y) (x < y ? x : y)
#define MAX(x, y) (x > y ? x : y)

using namespace std;

int main(){
	ll a, b, c;
	cin >> a >> b >> c;
	
	c %= 3;
	if(c == 0) cout << a << endl;
	else if(c == 1) cout << b << endl;
	else cout << (a ^ b) << endl;
}