#include<bits/stdc++.h>

using namespace std;

int main() {
  long long n;
  cin >> n;
  int a = 0, b = 0;
  while (n) {
    a += n % 10;
    if (n < 10) b += n - 1;
    else b += 9;
    n /= 10;
  }
  cout << max(a, b) << endl;
}
### Prompt

Your task is to create 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;

int main() {
  long long n;
  cin >> n;
  int a = 0, b = 0;
  while (n) {
    a += n % 10;
    if (n < 10) b += n - 1;
    else b += 9;
    n /= 10;
  }
  cout << max(a, b) << endl;
}
```