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

typedef long long  LL;
LL n;
int ans;

void work()
{
	scanf("%lld",&n),n++;
	while (n>9)  ans+=9,n/=10;
	ans+=n-1;
	printf("%d",ans);
}

int main()
{
	work();
	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;

typedef long long  LL;
LL n;
int ans;

void work()
{
	scanf("%lld",&n),n++;
	while (n>9)  ans+=9,n/=10;
	ans+=n-1;
	printf("%d",ans);
}

int main()
{
	work();
	return 0;
}

```