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# (Mono 4.6.2.0) (judge verdict: Runtime Error)

using System;
using System.Collections.Generic;

namespace Competitive
{
    internal class Program
    {
        public static void Main(string[] args)
        {
            int N = int.Parse(Console.ReadLine());

            List<int> digits = new List<int>();
            while (N > 0)
            {
                digits.Add(N % 10);
                N /= 10;
            }

            bool flag = true;
            for (int i = 0; i < digits.Count - 1; i++)
            {
                if (digits[i] != 9) flag = false;
            }
            
            int ret = 0;
            for (int i = 0; i < digits.Count - 1; i++)
            {
                ret += 9;
            }
            ret += digits[digits.Count - 1];
            if (!flag) ret -= 1;
            
            Console.WriteLine(ret);


        }
    }
}