n, k = gets.chomp.split.map(&:to_i)
s = gets.chomp

ls = []
for i in 0...n
  if s[i] == '(' 
    ls << i + 1
  else
    if i + 1 == k
      puts ls[-1]
      break
    elsif ls[-1] == k
      puts i + 1
      break
    else
      ls.delete_at(-1)
    end
  end
end