import java.util.Scanner; import java.util.stream.IntStream; public class Main{ static IntStream REPS(int v){return IntStream.range(0,v);} static IntStream REPS(int l,int r){return IntStream.rangeClosed(l,r);} static IntStream INS(int n){return REPS(n).map(i->getInt());} static Scanner s=new Scanner(System.in); static int getInt(){return Integer.parseInt(s.next());} static long getLong(){return Long.parseLong(s.next());} public static void main(String[]$){ long a=getLong(),b=getLong(); long[]v={a,b,a^b}; System.out.println(v[(int)(getLong()%3)]); } }