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

int main(){
    long long N;  cin >> N;
    N++;
    string s = to_string(N);
    int n = s.length();
    if(s[0]=='1'){
        cout << 9*(n-1) << endl;
    }else{
        cout << 9*(n-1) + (s[0]-'0' - 1) << endl;
    }
}

### Prompt

Please create a solution in Cpp 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 <bits/stdc++.h>
using namespace std;

int main(){
    long long N;  cin >> N;
    N++;
    string s = to_string(N);
    int n = s.length();
    if(s[0]=='1'){
        cout << 9*(n-1) << endl;
    }else{
        cout << 9*(n-1) + (s[0]-'0' - 1) << endl;
    }
}

```