#include <bits/stdc++.h>
using namespace std;



int main()
{
    long long n;
    int ans=0;
    cin>>n;
    n+=1;
    while(n>10){
        ans+=9;
        n/=10;
    }
    ans+=n-1;
    cout<<ans;


}

### Prompt

Your challenge is to write 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 <bits/stdc++.h>
using namespace std;



int main()
{
    long long n;
    int ans=0;
    cin>>n;
    n+=1;
    while(n>10){
        ans+=9;
        n/=10;
    }
    ans+=n-1;
    cout<<ans;


}

```