output_description: Print the number of ways to choose a pair of an even number and an odd number
  from the positive integers between 1 and K (inclusive).
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      K
attempt: x1, y1, x2, y2 = map(int, input().split())
  dx = abs(x1 - x2)
  dy = abs(y1 - y2)
  if x1 < x2 and y1 <= y2:
      x3 = x2 - dy
      y3 = y2 + dx
      x4 = x3 - dx
      y4 = y3 - dy
  elif x1 >= x2 and y1 < y2:
      x3 = x2 - dy
      y3 = y2 - dx
      x4 = x3 + dx
      y4 = y3 - dy
  elif x1 > x2 and y1 >= y2:
      x3 = x2 - dy
      y3 = y2 + dx
      x4 = x3 - dx
      y4 = y3 - dy
  elif x1 <= x2 and y1 > y2:
      x3 = x2 + dy
      y3 = y2 + dx
      x4 = x3 - dx
      y4 = y3 + dy
  print(x3, y3, x4, y4)
  
problem_description: Statement
  
  Find the number of ways to choose a pair of an even number and an odd number
  from the positive integers between 1 and K (inclusive). The order does not
  matter.
samples: [{"input": "3", "output": "2\n    \n\nTwo pairs can be chosen: (2,1) and (2,3).\n\n* * *"}, {"input": "6", "output": "9\n    \n\n* * *"}, {"input": "11", "output": "30\n    \n\n* * *"}, {"input": "50", "output": "625"}]