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: #!/usr/bin/env python3
  
  import sys, math, copy
  
  # import fractions, itertools
  # import numpy as np
  # import scipy
  
  HUGE = 2147483647
  HUGEL = 9223372036854775807
  ABC = "abcdefghijklmnopqrstuvwxyz"
  
  
  def main():
      def digsum(s):
          su = 0
          for c in s:
              su += int(c)
          return su
  
      def break_ith_dig(s, i1):
          assert 2 <= i1 <= dig
          if s[-i1] == "0":
              return s
          s = s[:-i1] + str(int(s[-i1]) - 1) + "9" * (i1 - 1)
          return s
  
      ns = input()
      dig = len(ns)
      ma = digsum(ns)
      for i in range(2, dig + 1):
          ns = break_ith_dig(ns, i)
          ma = max(ma, digsum(ns))
  
      print(ma)
  
  
  main()
  
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"}]