#include <iostream>
using namespace std;
long long n, s;
int main() {
	cin>>n;
	for(++n; n>9; n/=10) s += 9;
	cout<<s+n-1;
	return 0;
}
### Prompt

In CPP, your task is to solve 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 <iostream>
using namespace std;
long long n, s;
int main() {
	cin>>n;
	for(++n; n>9; n/=10) s += 9;
	cout<<s+n-1;
	return 0;
}
```