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

stack = Array.new
corresponds = Array.new( N )

S.split( "" ).each_with_index do | c, i |
	if c == '(' then
		stack.push( i )
	elsif c == ')' # damn '\n' !
		corresponds[i] = stack.last
		corresponds[ stack.last ] = i
		stack.pop
	end
end

puts corresponds[ K - 1 ] + 1