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: Accepted)

N = input()

ans = 0
for n in N:
    ans += int(n)

for i in range(len(N)):
    tmp = 0
    for j in range(i):
        tmp += int(N[j])

    tmp += int(N[i])-1

    if i < len(N):
        for _ in range(i+1, len(N)):
            tmp += 9

    if tmp > ans:
        ans = tmp

print(ans)