#include <bits/stdc++.h>
using namespace std;

long a, b, c, ans;
int main(){
cin >> a >> b >> c;
if(c%3==0){
ans = a;
}else if(c%3==1){
ans = b;
}else{
ans = (a^b);
}
printf("%ld\n", ans);
return 0;
}