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 {
	static Scanner sc = new Scanner(System.in);

	public static void main(String[] args) {
		long num = sc.nextInt();
		long ans = 1;

		for(long count = num; count > 1; count--) {
			ans = ans * count;
		}

		System.out.println(ans);
		ans = 0;
	}

}