#include<iostream>
using namespace std;

int main(){
    long long n, c = 0, ans, t;
    cin >> n;
    n++;
    t = n;
    while(t > 10){
        t /= 10;
        c++;
    }
    ans = t - 1 + 9 * c;
    cout << ans << endl;
    return 0;
}
### Prompt

Your challenge is to write 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>
using namespace std;

int main(){
    long long n, c = 0, ans, t;
    cin >> n;
    n++;
    t = n;
    while(t > 10){
        t /= 10;
        c++;
    }
    ans = t - 1 + 9 * c;
    cout << ans << endl;
    return 0;
}
```