#include <iostream>
#include <algorithm>
using namespace std;
int main(void){
    long long n,m=1;
    cin>>n;
    int k=0,l=n%10;
    for(long long i=n/10;i>0;i/=10){
        k++;
        l+=i%10;
        m*=10;
    }
    k=(n/m)-1+9*k;
    cout<<max(k,l)<<endl;
}

### 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 <algorithm>
using namespace std;
int main(void){
    long long n,m=1;
    cin>>n;
    int k=0,l=n%10;
    for(long long i=n/10;i>0;i/=10){
        k++;
        l+=i%10;
        m*=10;
    }
    k=(n/m)-1+9*k;
    cout<<max(k,l)<<endl;
}

```