#include<bits/stdc++.h>

using namespace std;

int main(){
	long long n;
	cin>>n;
	long long m=n;
	int sum=1;
	int ans2=0;
	while(m>=10)
	{
		ans2+=m%10;
		m/=10;
		sum++;
	}
	ans2+=m;
	int x=m;
	int ans1=x-1+(sum-1)*9;
	cout<<max(ans1,ans2);
	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<bits/stdc++.h>

using namespace std;

int main(){
	long long n;
	cin>>n;
	long long m=n;
	int sum=1;
	int ans2=0;
	while(m>=10)
	{
		ans2+=m%10;
		m/=10;
		sum++;
	}
	ans2+=m;
	int x=m;
	int ans1=x-1+(sum-1)*9;
	cout<<max(ans1,ans2);
	return 0;
}
```