#include<bits/stdc++.h>
using namespace std;

int main(){
	string s;
	cin>>s;
	
	bool jud=true;
	for(int i=1;i<s.size();++i){
		if(s[i]!='9'){
			jud=false;
			break;
		}
	}
	
	int ans=s[0]-'0';
	ans+=9*(s.size()-1);
	
	if(jud) cout<<ans<<endl;
	else cout<<ans-1<<endl;
}//解説参考.
### Prompt

Construct a cpp code solution to the problem outlined:

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<bits/stdc++.h>
using namespace std;

int main(){
	string s;
	cin>>s;
	
	bool jud=true;
	for(int i=1;i<s.size();++i){
		if(s[i]!='9'){
			jud=false;
			break;
		}
	}
	
	int ans=s[0]-'0';
	ans+=9*(s.size()-1);
	
	if(jud) cout<<ans<<endl;
	else cout<<ans-1<<endl;
}//解説参考.
```