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

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