#include <iostream>

using namespace std;


int main(void){
	unsigned long n,a=0,s=0;

	cin >> n;

	if(n < 10)a = n;
	else {
		while(n>=10){
			s=s+n%10;
			n=n/10;
			a=a+9;
		}
	a = a + n - 1;
	s = s+n%10;
	a = max(a,s);
	}

	cout << a << endl;

	return 0;
}

### Prompt

In CPP, your task is to solve the following problem:

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.

Examples

Input

100


Output

18


Input

9995


Output

35


Input

3141592653589793


Output

137

### Response

```cpp
#include <iostream>

using namespace std;


int main(void){
	unsigned long n,a=0,s=0;

	cin >> n;

	if(n < 10)a = n;
	else {
		while(n>=10){
			s=s+n%10;
			n=n/10;
			a=a+9;
		}
	a = a + n - 1;
	s = s+n%10;
	a = max(a,s);
	}

	cout << a << endl;

	return 0;
}

```