defmodule Main do
  def main do
    s = IO.read(:line) |> String.trim()

    solve(s) |> IO.puts
  end
  
  def solve(sd) do
    s = "abcdefghijklmnopqrstuvwxyz" |> String.codepoints()
    sd = sd |> String.codepoints()

    s
    |> Enum.with_index()
    |> Enum.find_value(fn {w, i} ->
      if w != Enum.at(sd, i), do: "#{w}to#{Enum.at(sd, i)}"
    end)
  end
end