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

int main(){
	long long val; cin >> val; int sum = 0; bool flg = 1;
	while(val / 10){flg &= val % 10 == 9; sum += 9; val /= 10;}
	sum += val % 10 - !flg; cout << sum; 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;

int main(){
	long long val; cin >> val; int sum = 0; bool flg = 1;
	while(val / 10){flg &= val % 10 == 9; sum += 9; val /= 10;}
	sum += val % 10 - !flg; cout << sum; return 0;
}

```