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 long Fact(int n){
		return n == 0 ? 1 : n * Fact(n - 1);
	}
	
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		int m = in.nextInt();
		System.out.println(Fact(m));
		in.close();
	}
}
				