let n = Scanf.sscanf (read_line ()) "%d" @@ fun n -> n

let code_a = int_of_char 'a'

let char_of_code code = char_of_int (code_a + code - 1)

let rec loop acc n =
  if n = 0 then acc |> List.map Char.escaped |> String.concat "" |> print_endline
  else loop (char_of_code (n mod 26) :: acc) (n / 26)

let () = loop [] n
