#include<bits/stdc++.h>
using namespace std;
string n;
int ans;
bool t;
int main(){
    cin >> n;
    for(int i = 1; i < n.size(); i++){
        if(n[i] != '9') t = true;
    }
    ans = (n.size() - 1)*9 + (n[0]-'0') - 1;
    if(!t) ans++;
    printf("%d\n", ans);
}
### Prompt

Please formulate 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<bits/stdc++.h>
using namespace std;
string n;
int ans;
bool t;
int main(){
    cin >> n;
    for(int i = 1; i < n.size(); i++){
        if(n[i] != '9') t = true;
    }
    ans = (n.size() - 1)*9 + (n[0]-'0') - 1;
    if(!t) ans++;
    printf("%d\n", ans);
}
```