#include<stdio.h>
#include<iostream>
#include<stdlib.h>
#include<string.h>
using namespace std;
#define ll long long
int main(void)
{
	ll n,nn,j,k,e;
	cin>>n;
	nn=n;j=0;k=0;e=1;while(nn>=10){k++;nn/=10;j=j*10+9;e*=10;}
	if(nn*e+j<=n)cout<<nn+k*9;
	else cout<<nn-1+k*9;
	return 0;
}
### Prompt

In Cpp, your task is to solve 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<stdio.h>
#include<iostream>
#include<stdlib.h>
#include<string.h>
using namespace std;
#define ll long long
int main(void)
{
	ll n,nn,j,k,e;
	cin>>n;
	nn=n;j=0;k=0;e=1;while(nn>=10){k++;nn/=10;j=j*10+9;e*=10;}
	if(nn*e+j<=n)cout<<nn+k*9;
	else cout<<nn-1+k*9;
	return 0;
}
```