defmodule Main do
  def main do
    IO.read(:line)
    |> String.trim()
    |> solve
    |> IO.puts()
  end

  def solve(n) do
    n
    |> String.to_charlist()
    |> Enum.reverse()
    |> each_slice_3
    |> Enum.map(fn x -> x |> Enum.reverse() |> Enum.concat(',') end)
    |> Enum.reverse()
    |> Enum.join()
    |> String.slice(0..-2)
  end

  def each_slice_3(list) do
    each_slice_3_rec(list, [])
  end

  def each_slice_3_rec(list, result) do
    case list do
      [a, b, c | d] ->
        each_slice_3_rec(d, result |> Enum.concat([[a, b, c]]))

      [] ->
        result

      l ->
        result |> Enum.concat([l])
    end
  end
end