#include <iostream>
#include <cstring>
#include <cstdio>
#include<string>
#include <algorithm>
#include <cmath>
using namespace std;
int main()
{
	long long n;
	cin >> n;
	n++;
	int s = 0;
	while (n > 9)
	{
		s += 9;
		n /= 10;
	}
	s += (n - 1);
	cout << s << endl;
	return 0;
}
### Prompt

Develop a solution in CPP 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>
#include <cstring>
#include <cstdio>
#include<string>
#include <algorithm>
#include <cmath>
using namespace std;
int main()
{
	long long n;
	cin >> n;
	n++;
	int s = 0;
	while (n > 9)
	{
		s += 9;
		n /= 10;
	}
	s += (n - 1);
	cout << s << endl;
	return 0;
}
```