using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Input N: ");

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

​

            int i = 1;

            int result = 0;

            int temp = 1;

            while (i <= n)

            {

                temp *= i;

                result += temp;

                i++;

            }

​

            Console.WriteLine("Result: {0}", result);

    }

}