import Control.Applicative ((<$>))
import Data.ByteString.Char8 (ByteString)
import qualified Data.ByteString.Char8 as B

main :: IO ()
main = do
  solve <$> B.getLine >>= print

solve :: ByteString -> Int
solve = g . B.foldl' f (0, 0, 0)
  where
    f (tc, rc, ec) c | c == 't' = (tc + 1, rc, ec)
                     | c == 'r' = (tc, rc + 1, ec)
                     | c == 'e' = (tc, rc, ec + 1)
                     | otherwise = (tc, rc, ec)
    g (tc, rc, ec) = min (min tc rc) (ec `div` 2)