output_description: Print the answer.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      a b c d
attempt: list1 = input()
  list2 = list1.split()
  a = int(list2[0])
  b = int(list2[1])
  c = int(list2[2])
  d = int(list2[3])
  
  # x = [i for i in range(a,b+1)]
  # y = [j for j in range(c,d+1)]
  
  x_min = a
  x_max = b
  y_min = c
  y_max = d
  
  answer_list = [x_max * y_max, x_max * y_min, x_min * y_max, x_min * y_min]
  
  print(max(answer_list))
  
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"}]