#include<cstdio>
long long n,n1,ans,num,s;
int main()
{
	scanf("%lld",&n);
	n1=n;
	for(;n/10;n/=10) num=num*10+9,ans+=9;
	if(n1==num+n*(num+1)) ans+=n;
	else ans+=n-1;
	printf("%lld\n",ans);
}
### Prompt

Create a solution in CPP for 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>
long long n,n1,ans,num,s;
int main()
{
	scanf("%lld",&n);
	n1=n;
	for(;n/10;n/=10) num=num*10+9,ans+=9;
	if(n1==num+n*(num+1)) ans+=n;
	else ans+=n-1;
	printf("%lld\n",ans);
}
```