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();

		String s=String.valueOf(N+1);	//読み込んだ文字列をlong型からString型に変更
		int len=s.length();	//文字列の長さをlenに格納
		int c=Integer.parseInt(s.substring(0, 1));	//文字列の頭文字をcに格納

		int ans=(c-1)+9*(len-1);	//N+1を考えることでansは常にこの式になる
		System.out.println(ans);

	}
}