#include <iostream>


int main() {
	long long n;
	std::cin >> n;
	n++;
	int ans = 0;
	while(n >= 10) {
		ans += 9;
		n /= 10;
	}
	ans += n - 1;
	std::cout << ans << '\n';
}
### Prompt

Please provide a cpp coded solution to the problem described below:

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>


int main() {
	long long n;
	std::cin >> n;
	n++;
	int ans = 0;
	while(n >= 10) {
		ans += 9;
		n /= 10;
	}
	ans += n - 1;
	std::cout << ans << '\n';
}
```