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

int digit(ll n){
  int i=0;
  while(n!=0){
    n/=10;
    i++;
  }
  return i;
}

int main(){
  int i,j,cnt=0;
  ll n;
  cin>>n;
  n++;
  ll a=n/(ll)round(pow(10,digit(n)-1));
  cout<<a-1+9*(digit(n)-1)<<endl;
}
### 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;
using ll=long long;

int digit(ll n){
  int i=0;
  while(n!=0){
    n/=10;
    i++;
  }
  return i;
}

int main(){
  int i,j,cnt=0;
  ll n;
  cin>>n;
  n++;
  ll a=n/(ll)round(pow(10,digit(n)-1));
  cout<<a-1+9*(digit(n)-1)<<endl;
}
```