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 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>


int main()
{
    long long int n,d,sum=0,a=0,x=0;

    scanf("%lld",&n);
    if(n<10) printf("%lld",n);
    else
    {
        while (n > 0)
        {
            d = n % 10;
            n /= 10;
            a++;
            if(d!=9) x=1;
        }
        //   printf("d=%lld a=%lld ",d,a);

        if(x==0) sum=a*9;
        else sum=((a-1)*9)+d-1;

        printf("%lld",sum);
    }

    return 0;
}