new_contents: """Leetcode 204. Count Primes
  Easy
  
  URL: https://leetcode.com/problems/count-primes/
  
  Count the number of prime numbers less than a non-negative number, n.
  
  Example:
  
  Input: 10
  Output: 4
  Explanation: There are 4 prime numbers less than 10, they are 2, 3, 5, 7.
  """
  
  class Solution(object):
      def countPrimes(self, n):
          """
          :type n: int
          :rtype: int
          """
          pass
  
  
  def main():
      pass
  
  
  if __name__ == '__main__':
      main()
  
subject: Add lc0204_count_primes.py