#include<cstdio>
#include<algorithm>
using namespace std;
typedef long long int ll;
ll ans(ll n){
	if(n<10) return n;
	else if(n%10==9) return 9 + ans(n/10);
	else return max(9+ans(n/10-1),n%10+ans(n/10));
}

int main(){
	ll n;
	scanf("%lld",&n);
	printf("%lld\n",ans(n));
}

### Prompt

Your challenge is to write a CPP solution to 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<cstdio>
#include<algorithm>
using namespace std;
typedef long long int ll;
ll ans(ll n){
	if(n<10) return n;
	else if(n%10==9) return 9 + ans(n/10);
	else return max(9+ans(n/10-1),n%10+ans(n/10));
}

int main(){
	ll n;
	scanf("%lld",&n);
	printf("%lld\n",ans(n));
}

```