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 (3.4.3) (judge verdict: Wrong Answer)

#digit sum
import sys
import numpy as np

N = int(input())
a = int(np.log10(N))
b = int(str(N)[0])
string = str(N)
poss = 0
count = 0
max_count = len(string) - 1
for s in string[1:]:
    if s is '9': 
        count += 1
if count is max_count:
    print(9 * a + b)
else:
    print(9 * a + b - 1)