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

  defp solve(s) do
    [
      Enum.count(s, &(&1 == ?t)),
      Enum.count(s, &(&1 == ?r)),
      Enum.count(s, &(&1 == ?e)) |> div(2)
    ]
    |> Enum.min()
  end
end