defmodule Main do
    def paren(str, n) do
        left_fn =
            fn ->
                s = str |> String.slice((n)..-1)
                r = ~r/^(\(*)\(\)(.*)$/
                n + _paren(s, r)
            end
        right_fn =
            fn ->
                s = str |> String.slice(0..(n - 2))
                r = ~r/^(.*)\(\)(\)*)$/
                n - _paren(s, r)
            end
        n_char = str |> String.graphemes |> Enum.at(n - 1)
        case n_char do
            "(" -> left_fn.()
            ")" -> right_fn.()
        end
    end
    defp _paren(str, re, acc \\ 0) do
        case Regex.run(re, str, capture: :all_but_first) do
            nil -> acc + 1
            [s1, s2] -> _paren(s1 <> s2, re, acc + 2)
        end
    end
    def main do

        inputs = IO.binread(:all) |> String.split

        k = inputs |> Enum.at(1) |> String.to_integer
        s = inputs |> Enum.at(2)

        IO.puts paren(s, k)

    end
end