output_description: If a good set of choices does not exist, print `-1`.
  
  If a good set of choices exists, print one such set of choices in the
  following format:
  
      
      
      M
      b_1 b_2 ... b_M
      
  
  where M denotes the number of boxes that will contain a ball, and b_1,\ b_2,\
  ...,\ b_M are the integers written on these boxes, in any order.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N
      a_1 a_2 ... a_N
attempt: print("-1")
  
problem_description: Statement
  
  There are N empty boxes arranged in a row from left to right. The integer i is
  written on the i-th box from the left (1 \leq i \leq N).
  
  For each of these boxes, Snuke can choose either to put a ball in it or to put
  nothing in it.
  
  We say a set of choices to put a ball or not in the boxes is good when the
  following condition is satisfied:
  
    * For every integer i between 1 and N (inclusive), the total number of balls contained in the boxes with multiples of i written on them is congruent to a_i modulo 2.
  
  Does there exist a good set of choices? If the answer is yes, find one good
  set of choices.
samples: [{"input": "3\n    1 0 0", "output": "1\n    1\n    \n\nConsider putting a ball only in the box with 1 written on it.\n\n  * There are three boxes with multiples of 1 written on them: the boxes with 1, 2, and 3. The total number of balls contained in these boxes is 1.\n  * There is only one box with a multiple of 2 written on it: the box with 2. The total number of balls contained in these boxes is 0.\n  * There is only one box with a multiple of 3 written on it: the box with 3. The total number of balls contained in these boxes is 0.\n\nThus, the condition is satisfied, so this set of choices is good.\n\n* * *"}, {"input": "5\n    0 0 0 0 0", "output": "0\n    \n\nPutting nothing in the boxes can be a good set of choices."}]