defmodule Main do
  def main do
    n = IO.gets("") |> String.trim() |> String.to_integer()

    n
    |> process([])
    |> List.to_string()
    |> IO.puts()
  end

  def process(0, acc), do: acc
  def process(n, acc) do
    code = rem(n-1, 26) + ?a
    next = div(n-1, 26)
    process(next, [code|acc])
  end

end
