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++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
typedef long long ll;
string s;
int main(){
	cin >> s;
	ll res = 0;
	
	bool flag = true;
	for(int i=0;i<s.length();i++){
		if ( flag && s[i] != '9' ) {
			flag = false;
			break;
		}
			
	}
	if ( flag ) res += s.length() * 9;
	else res += s[0] - '0' - 1 + (s.length() - 1) * 9;
	printf("%lld\n",res);
	return 0;
}