#include <cstdio>

typedef long long int64;

int main()
{
	int64 n;
	scanf("%lld", &n);
	n++;
	int ans = 0;
	while (n > 9) ans += 9, n /= 10;
	ans += n - 1;
	printf("%d\n", ans);
	return 0;
}
### Prompt

Please provide a CPP coded solution 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>

typedef long long int64;

int main()
{
	int64 n;
	scanf("%lld", &n);
	n++;
	int ans = 0;
	while (n > 9) ans += 9, n /= 10;
	ans += n - 1;
	printf("%d\n", ans);
	return 0;
}
```