#include <iostream>
#include <cmath>

using namespace std;

int main()
{
    long long n;
    string s;
    cin >> n;
    s = to_string(n);

    cout << ((s[0] - '0') + (((n + 1) % (long long)pow(10, s.size() - 1)) == 0 ? 0 : -1)) + (s.size() - 1) * 9 << endl;

    return 0;
}

### Prompt

In Cpp, your task is to solve 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>
#include <cmath>

using namespace std;

int main()
{
    long long n;
    string s;
    cin >> n;
    s = to_string(n);

    cout << ((s[0] - '0') + (((n + 1) % (long long)pow(10, s.size() - 1)) == 0 ? 0 : -1)) + (s.size() - 1) * 9 << endl;

    return 0;
}

```