#include<cstdio>
int main(void){
	long long n, a;
	scanf("%lld", &n);
	n++;
	a = 0;
	while (n >= 10){
		a += 9;
		n = n / 10;
	}
	a += n;
	a--;
	printf("%lld\n", a);
}
### Prompt

Develop a solution in Cpp to the problem described below:

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<cstdio>
int main(void){
	long long n, a;
	scanf("%lld", &n);
	n++;
	a = 0;
	while (n >= 10){
		a += 9;
		n = n / 10;
	}
	a += n;
	a--;
	printf("%lld\n", a);
}
```