new_contents: import sys
  import math
  
  args = sys.argv
  
  N = len(args) > 1 and int(sys.argv[1]) or 1000
  nsqrt = int((math.pow(N, 0.5)))
  is_prime = [False] * N
  
  for x in xrange(1, nsqrt):
      for y in xrange(1, nsqrt):
          n = 4 * (x * x) + (y * y)
          if n <= N and n % 12 in [1,5]:
              is_prime[n] = True
  
          n = 3 * (x * x) + (y * y)
          if n <= N and n % 12 is 7:
              is_prime[n] = True
  
          n = 3 * (x * x) - (y * y)
          if n <= N and x > y and n % 12 is 11:
              is_prime[n] = True
  
  is_prime[2] = True
  is_prime[3] = True
  
  primes = []
  for k, v in enumerate(is_prime):
      v and primes.append(k)
  
  print(len(primes))
  
subject: Add sieve of atkin in python