using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Vuvedi chislo");

        int n = int.Parse(Console.ReadLine());

        int f=1; 

               do 

            {

              f=f*n;

              f--;

            }      

            while (n>1) ;

           Console.WriteLine(f);

    }       

}