#include<stdio.h>
typedef long long ll;
int main()
{
	ll n;
	scanf("%lld", &n);
	ll t = 1;
	int c = 0;
	for (;;)
	{
		if (t * 10 > n)break;
		t *= 10;
		c++;
	}
	printf("%lld\n", (n + 1) / t - 1 + c * 9);
}
### Prompt

Create a solution in cpp for 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<stdio.h>
typedef long long ll;
int main()
{
	ll n;
	scanf("%lld", &n);
	ll t = 1;
	int c = 0;
	for (;;)
	{
		if (t * 10 > n)break;
		t *= 10;
		c++;
	}
	printf("%lld\n", (n + 1) / t - 1 + c * 9);
}
```