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 = input()
cnt = 0
n = len(N)
flg = 0
for i,d in enumerate(N):
    if int(d) == 9:
        cnt += int(d)
    else:
        if i == 0:
            cnt += int(N[i])-1 
            cnt += 9 * (n-i-1)
            break
        else:
            cnt += int(N[i-1])-1 
            cnt += 9 * (n-i-1)
            break
print(cnt)