output_description: Print the answer.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      a b c d
attempt: (
      a,
      b,
      c,
      d,
  ) = map(int, input().split())
  x = a * c
  y = a * d
  z = b * c
  w = b * d
  s = b * d
  if w < x and z < x and y < x:
      print(x)
  elif w < y and z < y and x < y:
      print(y)
  elif w < z and x < z and y < z:
      print(z)
  elif y < w and z < w and x < w:
      print(w)
  else:
      print(s)
  
problem_description: Statement
  
  Given are integers a,b,c and d. If x and y are integers and a \leq x \leq b
  and c\leq y \leq d hold, what is the maximum possible value of x \times y?
samples: [{"input": "1 2 1 1", "output": "2\n    \n\nIf x = 1 and y = 1 then x \\times y = 1. If x = 2 and y = 1 then x \\times y =\n2. Therefore, the answer is 2.\n\n* * *"}, {"input": "3 5 -4 -2", "output": "-6\n    \n\nThe answer can be negative.\n\n* * *"}, {"input": "-1000000000 0 -1000000000 0", "output": "1000000000000000000"}]