import java.util.Scanner;
 
public class Main {
	public static void main(String[] args) {
		Scanner scn = new Scanner(System.in);
		int n = scn.nextInt();
		long x = 1;
		for (int i = 2; i <= n; i++) {
			x = x * i;
		}
		System.out.println(x);
	}
}