#include <iostream>
#include <string>
using namespace std;
int main(void){
  int i;
  string n;
  cin >> n;
  for (i=1;i<n.size();i++) if (n[i]!='9') break;
  if (i==n.size()) cout << n[0]-'0'+9*(n.size()-1) << endl;
  else cout << n[0]-'0'-1+9*(n.size()-1) << endl;
  return 0;
}
### Prompt

Construct a cpp code solution to the problem outlined:

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>
#include <string>
using namespace std;
int main(void){
  int i;
  string n;
  cin >> n;
  for (i=1;i<n.size();i++) if (n[i]!='9') break;
  if (i==n.size()) cout << n[0]-'0'+9*(n.size()-1) << endl;
  else cout << n[0]-'0'-1+9*(n.size()-1) << endl;
  return 0;
}
```