#include <bits/stdc++.h>
using namespace std;
int main(){
  long long int N,n,K=1,X;cin>>N;n=N;
  while(n>9){n/=10;K++;}X=n+1;
  for(long long int i=1;i<K;i++)X*=10;
  if(N==X-1)cout<<n+9*K-9<<endl;
  else cout<<n+9*K-10<<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 <bits/stdc++.h>
using namespace std;
int main(){
  long long int N,n,K=1,X;cin>>N;n=N;
  while(n>9){n/=10;K++;}X=n+1;
  for(long long int i=1;i<K;i++)X*=10;
  if(N==X-1)cout<<n+9*K-9<<endl;
  else cout<<n+9*K-10<<endl;
}
```