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

int main() {
  
  int64_t N; cin >> N; N++;
  
  string S = to_string(N);
  
  int headDigit = stoi(S.substr(0, 1)) - 1;
  
  int sum = headDigit + 9 * (S.size() - 1);
  
  cout << sum << endl;
  
}
### 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 <bits/stdc++.h>
using namespace std;

int main() {
  
  int64_t N; cin >> N; N++;
  
  string S = to_string(N);
  
  int headDigit = stoi(S.substr(0, 1)) - 1;
  
  int sum = headDigit + 9 * (S.size() - 1);
  
  cout << sum << endl;
  
}
```