#include<iostream>

using namespace std;

int main(){
 long n;
  cin >> n;
  
  bool res=true;
  int k=1;
  
  while(n>9){
    k++;
    if(n%10!=9) res=false;
    n/=10;
  }

 if(res) cout << n+(k-1)*9 << endl;
 else cout << n+(k-1)*9-1 << endl;

}
### Prompt

Create a solution in CPP for 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;
  
  bool res=true;
  int k=1;
  
  while(n>9){
    k++;
    if(n%10!=9) res=false;
    n/=10;
  }

 if(res) cout << n+(k-1)*9 << endl;
 else cout << n+(k-1)*9-1 << endl;

}
```