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

  defp solve(s) do
    s
    |> String.to_charlist()
    |> count_tre([0, 0, 0])
    |> Enum.min()
  end

  defp count_tre(s, [t, r, e]) do
    cond do
      Enum.empty?(s) ->
        [t, r, e |> div(2)]

      true ->
        tl(s)
        |> count_tre(
          cond do
            hd(s) == ?t -> [t + 1, r, e]
            hd(s) == ?r -> [t, r + 1, e]
            hd(s) == ?e -> [t, r, e + 1]
            true -> [t, r, e]
          end
        )
    end
  end
end