#include <bits/stdc++.h>
using namespace std;
 
int main(){
	long long int a,n;
	cin >> n;
	n=n+1;
	while(n > 9){
		n = n /10;
		a=a+9;
    }
	a=a+n-1;
		cout << a << endl;
   }

### Prompt

Please formulate a CPP solution to 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 int a,n;
	cin >> n;
	n=n+1;
	while(n > 9){
		n = n /10;
		a=a+9;
    }
	a=a+n-1;
		cout << a << endl;
   }

```