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: Accepted)

#include <bits/stdc++.h>
using namespace std;
typedef long long int LL;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    
    char c;
    cin >> c;
    
    int cnt = 0;
    char d;
    bool ok = true;
    while(cin >> d){
        if( d != '9' ) ok = false;
        cnt++;
    }
    //~ cerr << ok << endl;
    if(ok){
        cout<< (c-'0') + 9*cnt;
    }else cout << (c-'1') + 9*cnt;
    
    cout << '\n';
}