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: Accepted)

#include<stdio.h>
int main()
{
	char N[17];
	int len;
	int jadge = 1;
	scanf("%s", N);
	len = strlen(N);
	int ans;

	//二桁目以下が全部９なのか
	for (int i = 1; i < len; i++)
	{
		if (N[i] != '9')
		{
			jadge = 0;
			break;
		}
	}
	//二桁目以下が全部９の場合
	if (jadge)
	{
		ans = N[0] - '0' + (9 * (len - 1));
	}
	else
	{
		ans = N[0] - '0' - 1 + (9 * (len - 1));
	}
	printf("%d\n", ans);
	return 0;
}