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

### Prompt

Create a solution in Cpp for 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;
long long n,s;
int main()
{
    cin>>n,n++;
    while(n>9)s+=9,n/=10;
    cout<<s+n-1;
    return 0;
}

```