import java.util.Scanner;
public class PJJJeden {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int k = 1;
        for (int i = 1; i <= a; i++) {
            k = k * i;
        }
      System.out.print(k);
    }
}