#include <bits/stdc++.h>
using namespace std;
 
int main() {
  long long N, cnt = 0; cin >> N;
  while (N >= 10) {
    if (N%10 < 9)
      N -= 10;
    N /= 10;
    cnt += 9;
  }
  cnt += N;
  cout << cnt << endl;
  return 0;
}
### 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;
 
int main() {
  long long N, cnt = 0; cin >> N;
  while (N >= 10) {
    if (N%10 < 9)
      N -= 10;
    N /= 10;
    cnt += 9;
  }
  cnt += N;
  cout << cnt << endl;
  return 0;
}
```