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.*;
import java.lang.*;


public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        String s = String.valueOf(n);
        int l = s.length();
        if (l == 1) {
            System.out.println(n);
        } else {
            boolean nine = true;
            for (int i = 1; i < l; i++) {
                if (s.charAt(i) != '9') {
                    nine = false;
                    break;
                }
            }
            if (nine) {
                System.out.println(9 * (l - 1) + n / (long)(Math.pow(10, l - 1)));
            } else {
                System.out.println(9 * (l - 1) + n / (long)(Math.pow(10, l - 1)) - 1);
            }

        }
    }
}