#include <bits/stdc++.h>
using namespace std;
#define ll long long
int main(){
  ll N,M,L=1;
  cin>>N;
  M=N;
  while(M>=10){
    M/=10;
    L++;
  }
  ll X=M,ans=M-1;
  while(L-1){
    X=X*10+9;
    ans+=9;
    L--;
  }
  cout<<((N==X)?ans+1:ans)<<endl;
}
### Prompt

Develop a solution in Cpp 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 ll long long
int main(){
  ll N,M,L=1;
  cin>>N;
  M=N;
  while(M>=10){
    M/=10;
    L++;
  }
  ll X=M,ans=M-1;
  while(L-1){
    X=X*10+9;
    ans+=9;
    L--;
  }
  cout<<((N==X)?ans+1:ans)<<endl;
}
```