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

Your task is to create 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<cstdio>
using namespace std;
typedef long long ll;
ll n,ans=0,ok=1;
int main()
{
	scanf("%lld",&n);
	while(n/10)
	{
		ans+=9;
		if(n%10<9)ok=0;
		n/=10;
	}
	ans+=n;
	if(!ok)ans--;
	printf("%lld\n",ans);
	return 0;
}
```