Task2

import java.util.Scanner;

public class Task2
{
    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);
        int num = sc.nextInt();
        int result = 0;
        for (int i = 0; i <=num; i++)
        {
            result += (i-1)*i;
        }
        System.out.println(result);
    }
}