output_description: Print the minimum possible value of S_{max} - S_{min}.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      H W
attempt: #!/usr/bin/env python3
  class V:
      def __init__(self, f, v=None):
          self.f = f
          self.v = v
  
      def __str__(self):
          return str(self.v)
  
      def __call__(self, n):
          if n is None:
              return self.v
  
          if self.v is None:
              self.v = n
              return self.v
          self.v = self.f(self.v, n)
  
  
  h, w = map(int, input().split())
  
  
  def minmax(*args):
      return max(args) - min(args)
  
  
  def sep(m, n):
      a = b = c = 0
      nn = n // 2
      ans = V(min, float("inf"))
  
      for i in range(1, m):
          a = i * n
          mm = (m - i) // 2
  
          # 横
          b, c = (m - i) * nn, (m - i) * (n - nn)
          ans(minmax(a, b, c))
  
          # 縦
          b, c = mm * n, (m - i - mm) * n
          ans(minmax(a, b, c))
  
      return ans.v
  
  
  print(min(sep(h, w), sep(w, h)))
  
problem_description: Statement
  
  There is a bar of chocolate with a height of H blocks and a width of W blocks.
  Snuke is dividing this bar into exactly three pieces. He can only cut the bar
  along borders of blocks, and the shape of each piece must be a rectangle.
  
  Snuke is trying to divide the bar as evenly as possible. More specifically, he
  is trying to minimize S_{max} \- S_{min}, where S_{max} is the area (the
  number of blocks contained) of the largest piece, and S_{min} is the area of
  the smallest piece. Find the minimum possible value of S_{max} - S_{min}.
samples: [{"input": "3 5", "output": "0\n    \n\nIn the division below, S_{max} - S_{min} = 5 - 5 = 0.\n\n![2a9b2ef47b750c0b7ba3e865d4fb4203.png](https://atcoder.jp/img/arc074/2a9b2ef47b750c0b7ba3e865d4fb4203.png)\n\n* * *"}, {"input": "4 5", "output": "2\n    \n\nIn the division below, S_{max} - S_{min} = 8 - 6 = 2.\n\n![a42aae7aaaadc4640ac5cdf88684d913.png](https://atcoder.jp/img/arc074/a42aae7aaaadc4640ac5cdf88684d913.png)\n\n* * *"}, {"input": "5 5", "output": "4\n    \n\nIn the division below, S_{max} - S_{min} = 10 - 6 = 4.\n\n![eb0ad0cb3185b7ae418e21c472ff7f26.png](https://atcoder.jp/img/arc074/eb0ad0cb3185b7ae418e21c472ff7f26.png)\n\n* * *"}, {"input": "100000 2", "output": "1\n    \n\n* * *"}, {"input": "100000 100000", "output": "50000"}]