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() {

    ios_base::sync_with_stdio(false); 
    cin.tie(NULL);  
    long long n;
    cin>>n;
    long long temp = n;
    int units = n % 10;
    int digits = 0;
    int sum = 0;
    int msb;
    while(n > 0) {
    	msb = n % 10;
    	n /= 10;
    	digits++; 
    }
    digits--;
    if(units >= 8)
    	sum += (digits * 9) + msb;
    else
    	sum += (digits * 9) + --msb;

    cout << sum;


	return 0;		
}