new_contents: def proper_divisors(n):
      for i in range(1, n):
          if n % i == 0:
              yield i
  
  
  def is_perfect(n):
      return n == sum(proper_divisors(n))
  
  
  def is_deficient(n):
      return n > sum(proper_divisors(n))
  
  
  def is_abundant(n):
      return n < sum(proper_divisors(n))
  
  
  abundants = set()
  for n in range(1, 28123):
      if is_abundant(n):
          abundants.add(n)
  
  abundants_sums = set(n + m for n in abundants for m in abundants)
  
  total = 0
  for n in range(1, 28123):
      if n not in abundants_sums:
          total += n
  print(total)
  
subject: Add 23