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 C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <bits/stdc++.h>

using namespace std;

int main(){
    long i;
    long n;
    int s = 0;
    int e = 0;
    cin >> n;
    i = n;
    s = s + i %10;
    do{
        i = i - i % 10;
        i = i / 10;
        s = s + i %10;
    }while(i/10 >=1);
    cout<< s;
    while(n/10 >=1){
        e = e + 1;
        n = n - n % 10;
        n = n / 10;
    }
    if(9*e+n-1 > s) s = 9*e+n-1;
    cout << s;
    return 0;
}