#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;

int main()
{
	string s;
	cin>>s;
	int len=s.length();
	int ans;
	ans=s[0]-'0'+(len-1)*9;
	int t=len-1;
	while (s[t]=='9') t--;
	if (t>0) ans-=1;
	cout<<ans<<endl;
	return 0; 
} 
### 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>
#include<cstdio>
#include<cstring>
using namespace std;

int main()
{
	string s;
	cin>>s;
	int len=s.length();
	int ans;
	ans=s[0]-'0'+(len-1)*9;
	int t=len-1;
	while (s[t]=='9') t--;
	if (t>0) ans-=1;
	cout<<ans<<endl;
	return 0; 
} 
```