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

}

### 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;
int S(long long x) {
if(x < 10) return x;
return (x%10) + S(x/10);
}
int main() {
long long s;
cin >> s;
int ans = S(s);
int cur = 0;
while(s/10) {
s/=10;
cur += 9;
ans = max(ans, cur + S(s-1));
}
cout << ans;

}

```