Problem:
Score : 300 points

Problem Statement

Find the maximum possible sum of the digits (in base 10) of a positive integer not greater than N.

Constraints

1\leq N \leq 10^{16}

N is an integer.

Input

Input is given from Standard Input in the following format:

N

Output

Print the maximum possible sum of the digits (in base 10) of a positive integer not greater than N.

Sample Input 1

100

Sample Output 1

18

For example, the sum of the digits in 99 is 18, which turns out to be the maximum value.

Sample Input 2

9995

Sample Output 2

35

For example, the sum of the digits in 9989 is 35, which turns out to be the maximum value.

Sample Input 3

3141592653589793

Sample Output 3

137

Solution in Python (3.8.2) (judge verdict: Runtime Error)

n=list(input())
n_list=[int(i) for i in n]
if n_list[0]!=1 and set(n_list)!=[9]:
  ans=9*(len(n_list)-1)+n_list[0]-1
  print(ans)
elif n_list[0]!=1 and set(n_list)==[9]:
  ans=len(n_list)*9
  print(ans)
elif n_list[0]+n_list[1]<=9:
  ans=(len(n_list)-1)*9
  print(ans)
else:
  ans=n_list[0]+n_list[1]-1+9*(len(n_list)-2)
  print(ans)