import Control.Applicative

main = do
  [n, k] <- map read . words <$> getLine
  s <- getLine
  let
    f [] _ _ = undefined
    f (c:s) xs@(y:ys) i
      | i == k && c == ')'= y
      | y == k && c == ')' = i
    f ('(':s) xs i = f s (i:xs) (i+1)
    f (')':s) (_:ys) i = f s ys (i+1)
    in print $ f s [] 1