output_description: Print the number of positive integers less than or equal to N that have an odd
  number of digits.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N
attempt: A = int(input())
  
  retval = 0
  if A == 100000:
      A = A - 1
  
  if A >= 10000:
      retval += A - 9999
      A = 9999
  
  if A >= 1000:
      A = 999
  
  if A >= 100:
      retval += A - 99
      A = 99
  
  if A >= 10:
      A = 9
  
  retval += A
  print(retval)
  
problem_description: Statement
  
  Given is an integer N. Find the number of positive integers less than or equal
  to N that have an odd number of digits (in base ten without leading zeros).
samples: [{"input": "11", "output": "9\n    \n\nAmong the positive integers less than or equal to 11, nine integers have an\nodd number of digits: 1, 2, \\ldots, 9.\n\n* * *"}, {"input": "136", "output": "46\n    \n\nIn addition to 1, 2, \\ldots, 9, another 37 integers also have an odd number of\ndigits: 100, 101, \\ldots, 136.\n\n* * *"}, {"input": "100000", "output": "90909"}]