main::IO()
main = do
  n:k:[] <-fmap (fmap read . words) $getLine
  ws <-getLine
  let me = ws !! (k-1)
      exe 0 xs =length xs
      exe n (x:xs) 
        |x==me = exe (n+1) xs
        |otherwise = exe (n-1) xs
  if me=='(' then
    print .(\x->n-x) . exe 1 . drop k $ws
  else
    print . (+1) .exe 1 . drop (n-k+1) . reverse $ws