#include <iostream>
using namespace std;
long long n, k, s, mx, t;
int main() {
	cin>>n;
	for(k=1; ; k*=10) {
		t = n/k*k;
		if(t==0) break;
		if(k>1) t--;
		for(s=0; t; t/=10) s += t%10;
		mx = max(mx, s);
	}
	cout<<mx;
	return 0;
}
### Prompt

Please provide a cpp coded solution to the problem described below:

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, k, s, mx, t;
int main() {
	cin>>n;
	for(k=1; ; k*=10) {
		t = n/k*k;
		if(t==0) break;
		if(k>1) t--;
		for(s=0; t; t/=10) s += t%10;
		mx = max(mx, s);
	}
	cout<<mx;
	return 0;
}
```