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 = int(input())

for i in range(17):
    if 10**i <=N <10**(i+1):
        m=i+1
        break

for j in range(1,10):
    if (10**(m-1))*j + 10**(m-1)-1 <=N< (j+1)*(10**(m-1))+10**(m-1)-1:
        a = j
        break

print(a+9*(m-1))