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;

public class Main {
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		
		int n = scan.nextInt();
		
		long bi = 1;
		
		for(int i=1;i<=n;i++)
		{
			bi *= i;
		}
		System.out.println(bi);
		
		scan.close();
	}
}