//Vol0 0019
#include<stdio.h>
int main()
{
	long long int r=1;
	int n,i;
	scanf("%d",&n);
	for(i=1;i<=n;i++){
		r*=i;
	}
	printf("%lld\n",r);
	return 0;
}
### Prompt

Your challenge is to write 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
//Vol0 0019
#include<stdio.h>
int main()
{
	long long int r=1;
	int n,i;
	scanf("%d",&n);
	for(i=1;i<=n;i++){
		r*=i;
	}
	printf("%lld\n",r);
	return 0;
}
```