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

  defp solve(s) do
    s
    |> String.replace(~r/[^tre]/, "")
    |> String.to_charlist()
    |> (fn t ->
          [
            Enum.count(t, &(&1 == ?t)),
            Enum.count(t, &(&1 == ?r)),
            Enum.count(t, &(&1 == ?e)) |> div(2)
          ]
        end).()
    |> Enum.min()
  end
end