import Control.Applicative ((<$>), (<*>))
import Data.ByteString.Char8 (ByteString)
import qualified Data.ByteString.Char8 as B

main :: IO ()
main = solve <$> (map read . words <$> getLine) <*> B.getLine >>= print

solve :: [Int] -> ByteString -> Int
solve [n, k] s = f 1 [] u
    where
        u = B.unpack s
        f i xs (c:cs) = if c == '('
                            then f (i + 1) (i : xs) cs
                            else if head xs == k
                                    then i
                                    else if i == k
                                            then head xs
                                            else f (i + 1) (tail xs) cs