#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

int main()
{
	ll i, n, s;
	
	scanf("%lld", &n);
	
	for(i=s=0;n>=10;n/=10,i++) s += n%10;
	
	printf("%lld\n", max(s + n, n-1 + 9*i));
	
	return 0;
}
### 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;

typedef long long ll;

int main()
{
	ll i, n, s;
	
	scanf("%lld", &n);
	
	for(i=s=0;n>=10;n/=10,i++) s += n%10;
	
	printf("%lld\n", max(s + n, n-1 + 9*i));
	
	return 0;
}
```