#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
	string s;cin>>s;
	int n=s.size(),a=s[0]-'0',ans;
	bool flg=true;
	for(int i=1;i<n;i++){if(s[i]!='9')flg=false;}
	if(flg)ans=a+9*(n-1);
	else ans=a+9*(n-1)-1;
	
cout<<ans<<endl;
}
### 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 <bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
	string s;cin>>s;
	int n=s.size(),a=s[0]-'0',ans;
	bool flg=true;
	for(int i=1;i<n;i++){if(s[i]!='9')flg=false;}
	if(flg)ans=a+9*(n-1);
	else ans=a+9*(n-1)-1;
	
cout<<ans<<endl;
}
```