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)

n=int(input())
k=list(str(n))
ans=0
for j in range(17):
    if n==10**j:
        ans=1
        break
for i in range(len(k)):
    k[i]=int(k[i])
if ans==1:
    print(9*(len(k)-1))
else:
    print(max(sum(k),9*len(k)-9+k[0]-1))