f :: [Char] -> [(Int, Char)]
f xs = zip [1..] xs

g :: [(Int, Char)] -> [Int]
g ys = [z - x + 1| (x, a) <- ys, (y, b) <- ys, (z, c) <- ys, x < y, y < z , a == 'c', b == 'w', c == 'w']

main :: IO ()
main = do
    s <- g . f <$> getLine
    putStrLn $ show $ if null s then -1 else minimum s