#include "bits/stdc++.h"
using namespace std;

int main() {
	long long N, P;
	int X;
	cin >> N;
	X = log10(N);
	P = pow(10, X);
	if ((N + 1) % P == 0) cout << N / P + X * 9;
	else cout << N / P + X * 9 - 1;
}
### Prompt

Your task is to create 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;

int main() {
	long long N, P;
	int X;
	cin >> N;
	X = log10(N);
	P = pow(10, X);
	if ((N + 1) % P == 0) cout << N / P + X * 9;
	else cout << N / P + X * 9 - 1;
}
```