#include<bits/stdc++.h>
#define INT long long int

using namespace std;
INT n, cnt, sum;
int main()
{
    cin>>n;
    while( n >= 10 ) sum += n%10, n/=10, cnt++;
    sum += n;
    if( cnt == 0 ) cout<<n<<endl;
    else cout<<max(sum, cnt*9+(n-1))<<endl;
    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>
#define INT long long int

using namespace std;
INT n, cnt, sum;
int main()
{
    cin>>n;
    while( n >= 10 ) sum += n%10, n/=10, cnt++;
    sum += n;
    if( cnt == 0 ) cout<<n<<endl;
    else cout<<max(sum, cnt*9+(n-1))<<endl;
    return 0;
}


```