output_description: Print the maximum possible sum of the digits (in base 10) of a positive
  integer not greater than N.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N
attempt: n = int(input())
  s = str(n)
  len_s = len(s)
  
  dp = [[0] * (len_s + 1) for i in range(2)]
  
  dp[0][1] = int(s[0])
  dp[1][1] = int(s[0]) - 1
  
  for i in range(1, len_s):
      for num in range(int(s[i]) + 1):
          dp[0][i + 1] = max(dp[0][i + 1], dp[0][i] + num)
  
      for num in range(int(s[i])):
          dp[1][i + 1] = max(dp[1][i + 1], dp[0][i] + num)
  
      for num in range(10):
          dp[1][i + 1] = max(dp[1][i + 1], dp[1][i] + num)
  
  print(max(dp[0][len_s], dp[1][len_s]))
  
problem_description: Statement
  
  Find the maximum possible sum of the digits (in base 10) of a positive integer
  not greater than N.
samples: [{"input": "100", "output": "18\n    \n\nFor example, the sum of the digits in 99 is 18, which turns out to be the\nmaximum value.\n\n* * *"}, {"input": "9995", "output": "35\n    \n\nFor example, the sum of the digits in 9989 is 35, which turns out to be the\nmaximum value.\n\n* * *"}, {"input": "3141592653589793", "output": "137"}]