main :: IO ()
main = getLine >>= print.solve


solve :: String -> Int
solve s = minimum [t, r, e]
    where
        xs = filter (\x -> x == 't' || x == 'r' || x == 'e') s
        t = length $ filter (\x -> x == 't') xs
        r = length $ filter (\x -> x == 'r') xs
        e = flip div 2 $ length $ filter (\x -> x == 'e') xs