#include<iostream>
using namespace std;
int main() {
	long long n; cin >> n;
	bool b = true; int cnt = 0;
	while (n >= 10) {
		if (n % 10 != 9)b = false;
		n /= 10;
		cnt++;
	}
	if (!b)n--;
	cout << cnt * 9 + n << 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; cin >> n;
	bool b = true; int cnt = 0;
	while (n >= 10) {
		if (n % 10 != 9)b = false;
		n /= 10;
		cnt++;
	}
	if (!b)n--;
	cout << cnt * 9 + n << endl;
	return 0;
}
```