#include<bits/stdc++.h>
using namespace std;
using ll=long long;
int main(){
  ll a;
  cin >> a;
  ll ans,k=0;
  ll n=a;
  while(a>9){
    a/=10;
    k++;
  }
  ans=9*k+a-1;
  if((n+1)%(ll)pow(10,k)==0)ans++;
  cout << ans;
}

### 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;
using ll=long long;
int main(){
  ll a;
  cin >> a;
  ll ans,k=0;
  ll n=a;
  while(a>9){
    a/=10;
    k++;
  }
  ans=9*k+a-1;
  if((n+1)%(ll)pow(10,k)==0)ans++;
  cout << ans;
}

```