import Data.List ( elemIndices )

main :: IO ()
main = do
    s <- reverse . dropWhile (/= 'w') . reverse . dropWhile (/= 'c') <$> getLine
    putStrLn . show $ solve s

solve :: [Char] -> Int
solve s = if (null s || length ys == 0) then -1 else minimum zs
    where
        xs = elemIndices 'c' s
        ys = tail $ map succ $ elemIndices 'w' s
        zs = [b - a | a <- xs, b <- ys, b - a >= 0]