#include<iostream>
#include<cstdlib>
using namespace std;

int main(){
    long long N;
    cin>>N;
    N++;

    string S=to_string(N);

    char t=S[0];
    long ans=9*(S.size()-1)+(S[0]-'0')-1;


    cout<<ans<<endl;
}
### 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>
#include<cstdlib>
using namespace std;

int main(){
    long long N;
    cin>>N;
    N++;

    string S=to_string(N);

    char t=S[0];
    long ans=9*(S.size()-1)+(S[0]-'0')-1;


    cout<<ans<<endl;
}
```