new_contents: #!/usr/bin/env python
  # -*- coding: utf-8 -*-
  # @Author: Zeyuan Shang
  # @Date:   2015-12-19 22:10:41
  # @Last Modified by:   Zeyuan Shang
  # @Last Modified time: 2015-12-19 22:10:47
  import math
  
  class Solution(object):
      def bulbSwitch(self, n):
          """
          :type n: int
          :rtype: int
          """
          return int(math.sqrt(n))
subject: add bulb-switcher