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

int main() {
  int64_t N;
  cin>>N;
  int Z=0,X=-1;
  while(N>=10){
    Z+=N%10;
    X+=9;
    N=N/10;
  }
  Z+=N;
  X+=N;
  cout<<max(Z,X)<<endl;
}
### Prompt

Please provide a CPP coded solution 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 <bits/stdc++.h>
using namespace std;

int main() {
  int64_t N;
  cin>>N;
  int Z=0,X=-1;
  while(N>=10){
    Z+=N%10;
    X+=9;
    N=N/10;
  }
  Z+=N;
  X+=N;
  cout<<max(Z,X)<<endl;
}
```