#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int main() {
    ll n, s;
    cin >> n;
    n++;
    while (n > 9) {
        s += 9;
        n /= 10;
    }
    cout << s + n - 1;
    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;
typedef long long ll;
int main() {
    ll n, s;
    cin >> n;
    n++;
    while (n > 9) {
        s += 9;
        n /= 10;
    }
    cout << s + n - 1;
    return 0;
}
```