#include<bits/stdc++.h>
using namespace std;
#define int long long 
int n;
signed main(){
	scanf("%lld",&n);
	int k,flag=1,cnt=0;
	while (n){
		k=n%10;
		n/=10;
		if (n)flag&=(k==9);
		cnt++;
	}
	printf("%lld\n",(cnt-1)*9+(flag?k:k-1));
}
### Prompt

Please provide a cpp coded solution to the problem described below:

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;
#define int long long 
int n;
signed main(){
	scanf("%lld",&n);
	int k,flag=1,cnt=0;
	while (n){
		k=n%10;
		n/=10;
		if (n)flag&=(k==9);
		cnt++;
	}
	printf("%lld\n",(cnt-1)*9+(flag?k:k-1));
}
```