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

### Prompt

Your task is to create 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<stdio.h>
int main(){
	int a;
	scanf("%d",&a);
	long long int b=1;
	for(int i=0;i<a;)b*=++i;
	printf("%lld\n",b);
}

```