_, K = gets.split.map(&:to_i)
S = gets.chomp

start_paren_index = 0
paren_table = {}
S.chars.each.with_index(1) do |paren, i|
  if paren == '('
    start_paren_index += 1
  else
    paren_table[start_paren_index] = i
    paren_table[i] = start_paren_index
    start_paren_index -= 1
  end
end

puts paren_table[K]