#include<iostream>
using namespace std;
typedef long long ll;

ll m =10;

ll keta(ll n){
  for(ll i=0;i<20;i++){
    if(n<m) return i;
    m *=10;
  }
}

int main(){
  ll n;
  cin >> n;
  cout << 9*keta((n+1)-1)+(10*(n+1)/m)-1;
}
### Prompt

Please formulate 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;

ll m =10;

ll keta(ll n){
  for(ll i=0;i<20;i++){
    if(n<m) return i;
    m *=10;
  }
}

int main(){
  ll n;
  cin >> n;
  cout << 9*keta((n+1)-1)+(10*(n+1)/m)-1;
}
```