#include<iostream>
using namespace std;
typedef long long ll;
int main(){
    ll n;
    cin>>n;
    ll ans=0;
    ll ct=0;
    while(n>=10){
        ans+=n%10;
        n/=10;
        ct++;
    }
    ans+=n;
    cout<<max(ans, ct*9+n-1)<<endl;
    return 0;
}
### Prompt

Generate 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>
using namespace std;
typedef long long ll;
int main(){
    ll n;
    cin>>n;
    ll ans=0;
    ll ct=0;
    while(n>=10){
        ans+=n%10;
        n/=10;
        ct++;
    }
    ans+=n;
    cout<<max(ans, ct*9+n-1)<<endl;
    return 0;
}
```