import Control.Applicative ((<$>))
import Data.List

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

solve :: String -> Int
solve s = g . foldl' f 200 $ ci
  where
    ci = findIndices (\x -> x == 'c') s
    wi = findIndices (\x -> x == 'w') s
    f d c = let wi' = dropWhile (< c) wi
            in if length wi' < 2 then d else min d (wi' !! 1 - c + 1)
    g x = if x == 200 then (-1) else x