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

int main()
{
	string N;
	cin >> N;

	int n = N.size();
	int ans = N[0] - '0' - 1;
	ans += (n - 1) * 9;
	if( N.substr( 1, n - 1 ) == string( n - 1, '9' ) || n == 1 ) {
		ans++;
	}

	cout << ans << endl;
}

### 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;

int main()
{
	string N;
	cin >> N;

	int n = N.size();
	int ans = N[0] - '0' - 1;
	ans += (n - 1) * 9;
	if( N.substr( 1, n - 1 ) == string( n - 1, '9' ) || n == 1 ) {
		ans++;
	}

	cout << ans << endl;
}

```