#include<iostream>
using namespace std;
int main()
{
	string n;
	cin>>n;
	if(n.size()==1){cout<<n<<endl;return 0;}
	for(int i=1;i<n.size();i++)
		if(n[i]!='9'){cout<<((n[0]-1)-'0'+9*(n.size()-1))<<endl;return 0;}
	cout<<n.size()*9+(n[0]-'0'-9)<<endl;
	return 0;
}

### Prompt

Please formulate 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()
{
	string n;
	cin>>n;
	if(n.size()==1){cout<<n<<endl;return 0;}
	for(int i=1;i<n.size();i++)
		if(n[i]!='9'){cout<<((n[0]-1)-'0'+9*(n.size()-1))<<endl;return 0;}
	cout<<n.size()*9+(n[0]-'0'-9)<<endl;
	return 0;
}

```