#10872 - java 팩토리얼

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