#include <bits/stdc++.h>

#define For(i, j, k) for (int i = j; i <= k; i++)

using namespace std;

long long x;
int ans;

int main() {

	scanf("%lld", &x);	
	++x;
	while (x >= 10) x /= 10, ans += 9;
	ans += x - 1;
	printf("%d\n", ans);

	return 0;
}
### Prompt

Your challenge is to write 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>

#define For(i, j, k) for (int i = j; i <= k; i++)

using namespace std;

long long x;
int ans;

int main() {

	scanf("%lld", &x);	
	++x;
	while (x >= 10) x /= 10, ans += 9;
	ans += x - 1;
	printf("%d\n", ans);

	return 0;
}
```