#include <iostream>
#include <string>
using namespace std;

int main()
{
  string s;
  cin >> s;

  int ans = 0;
  for(int i = s.size()-1; i > 0; i--){
    ans += 9; 
    if(s[i] != '9'){
      s[i-1]--;
    }
  }

  ans += s[0] - '0';
  cout << ans << endl;
  
  return 0;
}

### 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 <iostream>
#include <string>
using namespace std;

int main()
{
  string s;
  cin >> s;

  int ans = 0;
  for(int i = s.size()-1; i > 0; i--){
    ans += 9; 
    if(s[i] != '9'){
      s[i-1]--;
    }
  }

  ans += s[0] - '0';
  cout << ans << endl;
  
  return 0;
}

```