n,k = gets.split.map(&:to_i)
s = gets.chomp.chars
stack = []
indexes = Array.new(n,-1)
s.each_with_index do |v,i|
    if v == '('
        stack.push(i)
    else
        half = stack.pop
        indexes[half] = i
        indexes[i] = half
    end
end
puts indexes[k-1] + 1