let () =
  let x, y, l = Scanf.scanf "%d %d %d " (fun x y l -> x, y, l) in
  let move v = (float v) /. (float l) |> ceil |> truncate in
  let d =
    if y >= 0 then begin
      if x = 0 then move y else move y + 1 + move (if x < 0 then (-x) else x)
    end else
      1 + move (if x < 0 then (-x) else x) + 1 + move (-y) in
  Printf.printf "%d\n" d