s=[]
n,k=gets.split.map(&:to_i)
k-=1
gets.chomp.chars.each_with_index{|c,idx|
	if c==?(
		s.push [c,idx]
	else
		d,jdx=s.pop
		if idx==k
			p jdx+1
			exit
		end
		if jdx==k
			p idx+1
			exit
		end
	end
}