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
import java.util.Scanner;
	class Main{

		public static void main(String[] args){
	Scanner sc=new Scanner(System.in);
int su;
su=sc.nextInt();
long kei=1;
for(int i=1;i<=su;i++){
	kei=kei*i;
}
	
System.out.println(kei);	
	}
	}
	    