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 n;

  scanf("%lld",&n);
  int m=n;
  int i=1;
  int j=1;
  while(n>=10){
    n=n/10;
    i++;
    j=j*10;
  }
  if((m+1)%j==0){
    printf("%lld\n",n+9*(i-1));
  }
  else{
    printf("%lld\n",n-1+9*(i-1));
  }

  return 0;
}