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

const int MOD = (int)1e9+7;

int main(){
  long long N;
  cin >> N;

  N++;
  int ans=0;
  while(N>9){
    ans+=9;
    N/=10;
  }
  ans+=N-1;
  cout << ans << endl;

  return 0;
}

### 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;

const int MOD = (int)1e9+7;

int main(){
  long long N;
  cin >> N;

  N++;
  int ans=0;
  while(N>9){
    ans+=9;
    N/=10;
  }
  ans+=N-1;
  cout << ans << endl;

  return 0;
}

```