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 f = scan.nextInt();
		long tmp = 1;
		for(int i = 1; i <= f; i++)
		{
			tmp *= i;
		}
		System.out.println(tmp);
	}

}