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
#include<stdio.h>

int main(void){
	double ans=1;
	int n,i;
	scanf("%d",&n);
	for(i=1;i<=n;i++)ans=ans*i;
	
	printf("%0.0f\n",ans);
return 0;
}