#include<iostream>
#include<cmath>
#include<string>
#include<algorithm>
using namespace std;
int main(){

 long long int n;
cin >> n;

long long int f = log10(n+1);

long long int t = (n+1) / pow(10,f);

cout << t - 1 + ( 9 * f );

return 0;
}
### 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<cmath>
#include<string>
#include<algorithm>
using namespace std;
int main(){

 long long int n;
cin >> n;

long long int f = log10(n+1);

long long int t = (n+1) / pow(10,f);

cout << t - 1 + ( 9 * f );

return 0;
}
```