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: Runtime Error)

s = input()
n = int(s)

if s[-1] != "9":
    n1 = n - int(s[-1]) +1
    s1 = str(n1)

ans1 = 0
for i in range(len(s1)):
    ans1 += int(s[i])

m = str(int(s[0]) - 1) + (len(s) - 1) * "9" 
ans2 = 0
for i in range(len(m)):
    ans2 += int(m[i])

print(max(ans1, ans2))