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

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