#include <iostream>
using namespace std;

int main(void){
	int n;
	long long int sum,i;
	cin>>n;
	sum=1;
	for(i=1;i<=n;i++){
		sum=i*sum;
	}
	cout<<sum<<endl;

	return 0;
}
### Prompt

Please formulate a CPP solution to the following problem:

Write a program which reads an integer n and prints the factorial of n. You can assume that n ≤ 20.



Input

An integer n (1 ≤ n ≤ 20) in a line.

Output

Print the factorial of n in a line.

Example

Input

5


Output

120

### Response

```cpp
#include <iostream>
using namespace std;

int main(void){
	int n;
	long long int sum,i;
	cin>>n;
	sum=1;
	for(i=1;i<=n;i++){
		sum=i*sum;
	}
	cout<<sum<<endl;

	return 0;
}
```