#include<iostream>
#include<math.h>
using namespace std;
int main()
{
    long long x;
    cin>>x;
    int k=log10l(x);
    long long r=pow(10,(int)log10l(x));
    if((x+1)%r==0)cout<<x/r+9*k<<endl;
    else cout<<x/r+9*k-1<<endl;
    return 0;
}
### Prompt

Your task is to create 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<math.h>
using namespace std;
int main()
{
    long long x;
    cin>>x;
    int k=log10l(x);
    long long r=pow(10,(int)log10l(x));
    if((x+1)%r==0)cout<<x/r+9*k<<endl;
    else cout<<x/r+9*k-1<<endl;
    return 0;
}
```