import Data.List (elemIndex)

data Result = SUCCESS | FAILURE
    deriving (Show)

count :: Eq a => a -> [a] -> Int
count n xs = length $ filter (\x -> x == n) xs

solve :: Integral a => String -> a -> String -> Result
solve sb n sa
    | ob /= oa  = SUCCESS
    | d > n     = SUCCESS
    | otherwise = FAILURE
    where
        ob     = count 'o' sb
        oa     = count 'o' sa
        xb     = count 'x' sb
        xa     = count 'x' sa
        c      = if ob < xb then 'o' else 'x'
        Just d = fmap (fromIntegral . abs) $ ((-) <$> (elemIndex c sb) <*> (elemIndex c sa))

main = do
    sb <- getLine
    n  <- readLn
    sa <- getLine
    print $ solve sb n sa