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>
#include<math.h>
 
int main(){
  long n,i=0,flag=0,j;
  scanf("%ld",&n);
  if(n>10&&(int)log10(n)!=(int)log10(n+1)) flag=1;
  i=(int)log10(n);
  for(j=0;j<i;j++) n/=10;
  if(!i) printf("%ld\n",n);
  else printf("%ld\n",i*9-1+flag+n);
  
}