#include<bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
  int N;
  cin>>N;
  cout<<(to_string(N).size()-1LL)*9+(N+1)/(int)pow(10LL,to_string(N).size()-1LL)-1<<endl;
}
### 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<bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
  int N;
  cin>>N;
  cout<<(to_string(N).size()-1LL)*9+(N+1)/(int)pow(10LL,to_string(N).size()-1LL)-1<<endl;
}
```