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 = input()
  a = [int(c) for c in N]
  naga = len(a)
  for i in range(naga):
      if a[i] < 9:
          a[i] -= 1
          for j in range(i + 1, naga):
              a[j] = 9
          break
  if a[naga - 1] != 9:
      a[naga - 2] -= 1
      a[naga - 1] = 9
  print(sum(a))
  
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"}]