output_description: Print an integer representing the area of the regular dodecagon.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      r
attempt: N = int(input())
  As = list(map(int, input().split()))
  As.insert(0, 0)
  Ans = [0 for _ in range(N + 1)]
  Ans[N] = As[N]
  for i in range(N - 1, 0, -1):
      p = i * 2
      s = 0
      while p <= N:
          s += Ans[p]
          p += i
      Ans[i] = 0 if s % 2 == As[i] else 1
  M = sum(Ans)
  print(M)
  if M > 0:
      bs = ""
      for i in range(1, N + 1):
          if Ans[i] != 0:
              bs += "%d " % i
      bs = bs.rstrip(" ")
      print(bs)
  
problem_description: Statement
  
  It is known that the area of a regular dodecagon inscribed in a circle of
  radius a is 3a^2.
  
  Given an integer r, find the area of a regular dodecagon inscribed in a circle
  of radius r.
samples: [{"input": "4", "output": "48\n    \n\nThe area of the regular dodecagon is 3 \\times 4^2 = 48.\n\n* * *"}, {"input": "15", "output": "675\n    \n\n* * *"}, {"input": "80", "output": "19200"}]