#include<iostream>
#include<string>
#include<cmath>

using namespace std;

int main(){
    long long n,k;
    cin >> n;
    n++;
    k = int(log10(n));
    for(int i=0;i<k;i++)n/=10;
    cout << (n-1)+k*9 << endl;
    return 0;
}
### 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<iostream>
#include<string>
#include<cmath>

using namespace std;

int main(){
    long long n,k;
    cin >> n;
    n++;
    k = int(log10(n));
    for(int i=0;i<k;i++)n/=10;
    cout << (n-1)+k*9 << endl;
    return 0;
}
```