#include <iostream>
using namespace std;

int main() {
	long N; cin >> N;
	++N;
	int i;
	for(i=0; N>10; ++i) N /= 10;
	cout << N-1 + 9*i << endl;
	return 0;
}
### Prompt

Your task is to create 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 N; cin >> N;
	++N;
	int i;
	for(i=0; N>10; ++i) N /= 10;
	cout << N-1 + 9*i << endl;
	return 0;
}
```