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 <string.h>
#include <math.h>

#define LINE_BUF_SIZE 1024

int main(){

    int i,j,k;
    int length,first;
    long int N,value;
    char line[LINE_BUF_SIZE];
    int count = 0;

    fgets(line,sizeof(line),stdin);
    sscanf(line,"%ld",&value);
    length = strlen(line);
    
        if(strncmp(&line[0],"2",1)==0){
            first = 2;
        }

        if(strncmp(&line[0],"3",1)==0){
            first = 3;
        }

        if(strncmp(&line[0],"4",1)==0){
            first = 4;
        }

        if(strncmp(&line[0],"5",1)==0){
            first = 5;
        }

        if(strncmp(&line[0],"6",1)==0){
            first = 6;
        }

        if(strncmp(&line[0],"7",1)==0){
            first = 7;
        }

        if(strncmp(&line[0],"8",1)==0){
            first = 8;
        }

        if(strncmp(&line[0],"9",1)==0){
            first = 9;
            count  = 1;
            for(j=1;j<length-1;j++){
                if(strncmp(&line[j],"9",1)==0){
                    count += 1;
                }
            }
        }

        if(strncmp(&line[0],"9",1)!=0){
            for(j=1;j<length-1;j++){
                    if(strncmp(&line[j],"9",1)==0){
                        count += 1;
                    }
            }
        }

  //printf("%d,%d\n",length,count);

    if(value < 10){
       printf("%ld",value);
        return 0;
    }

    if(count == length-1){  /*全て9の場合*/
        printf("%d",9*(length-1));
        return 0;
    }

    else if(strncmp(&line[0],"1",1)==0){    /*先頭が1の場合*/
        if(count == length-2){
            printf("%d",9*(length-2)+1);
            return 0;
        }
        printf("%d",9*(length-2));
        return 0;
    }

    else if(strncmp(&line[0],"9",1)==0){   /*先頭が9の場合で、全てが9ではない場合*/
            printf("%d",9*(length-2)+8);
            //printf("koko\n");
            return 0;
    }

    else{   /*それ以外*/
        printf("%d",9*(length-2)+first-1);
    }

/*
    if(strncmp(&line[0],"1",1)==0 && (count != length-2)){
        printf("%d\n",9*(length-2));
    }

    else if(strncmp(&line[0],"1",1)==0 && (count == length-2)){
        printf("%d\n",9*(length-2)+first);
    }
    
    else if(strncmp(&line[0],"1",1)!=0 && (count == length-2)){
        printf("%d\n",9*(length-2)+first-1);
    }
    
    else if(first != 9 && (count == length-2)){
        printf("%d\n",9*(length-2)+(first-1));
    }

    else if(first == 9 && (count == length-1)){
        printf("%d\n",9*(length-1));
    }

    else if(first == 9 && (count != length-1)){
        printf("%d\n",9*(length-2)+(first-1));
    }
*/
//    printf("%d\n",first);
//    printf("%s\n", line);
//    printf("%ld\n", N);

    return 0;
}