#include <iostream>

using namespace std;

int main()
{
    long long x,digits=0,first;
    cin>>x;
    x++;
    while (x>0){
        first = x%10;
        digits++;
        x = (x-x%10)/10;
    }

    cout<<first-1+9*(digits-1)<<endl;



    return 0;
}

### Prompt

Develop a solution in CPP 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 <iostream>

using namespace std;

int main()
{
    long long x,digits=0,first;
    cin>>x;
    x++;
    while (x>0){
        first = x%10;
        digits++;
        x = (x-x%10)/10;
    }

    cout<<first-1+9*(digits-1)<<endl;



    return 0;
}

```