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(){
	char n[20];
	scanf("%s",&n);
	int len = strlen(n);
	
	int all9 = 1; // all number *expect the first digil*   is 9
	for(char* i = n+1; *i != NULL; i++){
		if( *i != '9' ){
			all9 = 0;
			break;
		}
	}
	
	int ret = 9 * (len - 1);

	n[1] = NULL;
	ret += atoi( n );
	if( ! all9 ) ret -= 1;

	printf("%d %d\n", ret, all9);
	
	return 0;
}