#include <bits/stdc++.h>
using namespace std;
int main(void) {
	long long a = 0, n; cin >> n;
 	for (++n; n > 9; n /= 10) {
    	a += 9; }
    cout << a + n - 1 << endl;
	return 0; 
}
### Prompt

Please create a solution in CPP 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(void) {
	long long a = 0, n; cin >> n;
 	for (++n; n > 9; n /= 10) {
    	a += 9; }
    cout << a + n - 1 << endl;
	return 0; 
}
```