#include<bits/stdc++.h>
using namespace std;
int main () {
  long long int n;
  cin >> n;
  long long int f = log10(n + 1);
  long long int t = (n + 1) / pow(10, f);
  cout << t - 1 + ( 9 * f );
}

### Prompt

Construct a Cpp code solution to the problem outlined:

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 int n;
  cin >> n;
  long long int f = log10(n + 1);
  long long int t = (n + 1) / pow(10, f);
  cout << t - 1 + ( 9 * f );
}

```