public class main{
    public static void main(String[] args) {
        try{
            int a,b;
            Scanner in=new Scanner(System.in);
            a=in.nextInt();
            
            in.close();
            b=1;
            for(int i=1;i<=a;i++)
            {
            	b*=i;
            }
            System.out.print(b);
        }catch(Exception e){
            System.out.println("Input error!");
        }
    }
};