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
public class Main {
	static int n = new java.util.Scanner(System.in).nextInt();

	public static void main(String[] args) {

		long ans = 1;
		for (int i = 1; i <= n; i++) {
			ans = ans * i;
		}
		System.out.println(ans);

	}
}