#include <iostream>
int main(){
long long n,p=-1,q=1,r=0;
std::cin>>n;
long long x=n;
while(x){p++;q*=10;r+=x%10;x/=10;}
if(n>9&& (n+1)*10%q!=0)std::cout<<p*9+((n*10)/q)-1;
else std::cout<<r;
}
### 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 <iostream>
int main(){
long long n,p=-1,q=1,r=0;
std::cin>>n;
long long x=n;
while(x){p++;q*=10;r+=x%10;x/=10;}
if(n>9&& (n+1)*10%q!=0)std::cout<<p*9+((n*10)/q)-1;
else std::cout<<r;
}
```