#include<cstdio>
long long n;
int main() {
	scanf("%lld", &n);
	long long t = 1, nn = n, s = 0;
	while (nn/10) {
		nn /= 10;
		t *= 10;
		s += 9;
	}
	if ((nn + 1)*t - 1 <= n) {
		s += nn;
	}
	else s += (nn - 1);
	printf("%lld\n", s);
}
### Prompt

Please formulate 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>
long long n;
int main() {
	scanf("%lld", &n);
	long long t = 1, nn = n, s = 0;
	while (nn/10) {
		nn /= 10;
		t *= 10;
		s += 9;
	}
	if ((nn + 1)*t - 1 <= n) {
		s += nn;
	}
	else s += (nn - 1);
	printf("%lld\n", s);
}
```