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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.*;

public class Main{

    public static void main(String args[]){
        Scanner sc = new Scanner(System.in);
        
        long N = sc.nextLong();

        long sum = 0;
        sc.close();
        int count = 0;
        int count9 = 0;

        if(N / 10 == 0){
            sum = N;
        } else{
            while(N/10 != 0){
                count++;
                if(N%10 == 9)
                    count9++;
                sum += 9;
                N /= 10;
            }
            if(count9 != count)
                sum += N-1;
            else
                sum += N;
        }

        System.out.println(sum);
    }
}