//java版//
import java.util.Scanner;
public class Main{
public static void main(String[] args){
Scanner sc=new Scanner(System.in);
int n=sc.nextInt();
int s=factorial(n);
System.out.println(s);
}
public static int factorial(int n){
if(n==0||n==1){
return 1;
}else{
return n*factorial(n-1);
}
}
}