public class Main{
	public static long factorial(int a){
		if (a == 0)
        	return 1;
        else
        	return a*factorial(a - 1);
		}
 
	public static void main (String[] args) throws java.lang.Exception 	{
		java.util.Scanner i = new java.util.Scanner(System.in);
		int a;
		int n = i.nextInt();
        System.out.print(factorial(n));
	}
}