{-# LANGUAGE BangPatterns #-}

module Main where

import Control.Monad

count :: String -> (Int, Int, Int)
count xs = iter 0 0 0 xs
  where
    iter !t !r !e []     = (t, r, e)
    iter !t !r !e (y:ys)
        | y == 't'  = iter (t + 1) r e ys
        | y == 'r'  = iter t (r + 1) e ys
        | y == 'e'  = iter t r (e + 1) ys
        | otherwise = iter t r e ys

main :: IO ()
main = do
    ss <- getLine
    let (t, r, e) = count ss
    print $ minimum [t, r, e `div` 2]