#include <iostream>
#define ll long long
using namespace std;

void solve(ll a,ll b,ll q)
{
	if(q % 3 == 1)	cout << a;
	else if(q % 3 == 2)	cout << b;
	else{
		cout << (a^b);
	}
}
int main() {
	ll a,b,q;
	cin >> a >> b >> q;
	solve(a,b,q);
	return 0;
}