import Data.List

main = do
 [_,k] <- map read . words <$> getLine
 bs <- getLine
 print (bracket k bs)

bracket :: Int -> String -> Int
bracket k = head . delete k . concat . filter (elem k) . fst . foldr idx ([],[]) . zip [1..]
 where
  idx (i,'(') (acc,((j,')'):stack)) = ([i,j]:acc, stack)
  idx ib (acc,stack) = (acc, ib:stack)