#include <iostream>

using namespace std;

int main(){
	long long N;
	long long tmp = 0;
	cin >> N;
	while (N >= 10) {
		if (N % 10 != 9) {
			N -= 10;
		}
		tmp += 9;
		N /= 10;
	}
	tmp += N;
	cout << tmp << endl;

	return 0;
}


### Prompt

Your challenge is to write a CPP solution to 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(){
	long long N;
	long long tmp = 0;
	cin >> N;
	while (N >= 10) {
		if (N % 10 != 9) {
			N -= 10;
		}
		tmp += 9;
		N /= 10;
	}
	tmp += N;
	cout << tmp << endl;

	return 0;
}


```