let () =
  let f0, f1, n = Scanf.scanf "%d %d %d " (fun f0 f1 n -> f0, f1, n) in
  match n mod 3 with
  | 0 -> Printf.printf "%d\n" f0
  | 1 -> Printf.printf "%d\n" f1
  | _ -> Printf.printf "%d\n" (f0 lxor f1)