#include<iostream>
#include<algorithm>
#include<cmath>
#include<iomanip>
#include<map>
using namespace std;
int main() {
  long long n,ans=0;
  cin >> n;
  n++;
  while(n>9) {
    n/=10;
    ans++;
  }
  cout << n-1+ans*9 << endl;
}

### 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<iostream>
#include<algorithm>
#include<cmath>
#include<iomanip>
#include<map>
using namespace std;
int main() {
  long long n,ans=0;
  cin >> n;
  n++;
  while(n>9) {
    n/=10;
    ans++;
  }
  cout << n-1+ans*9 << endl;
}

```