#include<cstdio>
#include<iostream>
using namespace std;
long long x;
int ans=0,p;
int main()
{
	scanf("%lld",&x);
	while (x>=10)
	{
		if (x%10!=9) p=1;
		ans+=9;
		x/=10;
	}
	ans+=x-p;
	printf("%d",ans);
}
### Prompt

Construct a cpp code solution to the problem outlined:

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<cstdio>
#include<iostream>
using namespace std;
long long x;
int ans=0,p;
int main()
{
	scanf("%lld",&x);
	while (x>=10)
	{
		if (x%10!=9) p=1;
		ans+=9;
		x/=10;
	}
	ans+=x-p;
	printf("%d",ans);
}
```