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);
	}
}