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: def add(n):
      return n + 1
  
  
  if __name__ == "__main__":
      n = int(input())
      buf = input().split()
      a = [int(s) for s in buf]
  
      boxes = [0] * n
  
      for i in reversed(range(n)):
          pick_boxes = boxes[i :: i + 1]
          pick_boxes.pop(0)
          if pick_boxes:
              if (sum(pick_boxes) % 2) == a[i]:
                  boxes[i] = 0
              else:
                  boxes[i] = 1
          else:
              boxes[i] = a[i]
  
      box_name = [i for i, x in enumerate(boxes) if x == 1]
      box_name = list(map(add, box_name))
      print(len(box_name))
      if len(box_name) != 0:
          box_name = " ".join(map(str, box_name))
          print(box_name)
  
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"}]