/*
 * Problem #6
 * The sum of the squares of the first ten natural numbers is,
 * 1^2 + 2^2 + ... + 10^2 = 385
 * The square of the sum of the first ten natural numbers is,
 * (1 + 2 + ... + 10)^2 = 55^2 = 3025
 * Hence the difference between the sum of the squares of the first ten natural numbers and the square of the sum is 3025 − 385 = 2640.
 * Find the difference between the sum of the squares of the first one hundred natural numbers and the square of the sum.
 */
using System;

public class Problem6
{
	public void Main()
	{
		Int64 sum_of_squares = 0;
		Int64 sum = 0;
		for (int i = 1; i <= 100; i++)
		{
			sum += i;
			sum_of_squares += (i*i);
		}
		Console.WriteLine( (sum * sum) - sum_of_squares );
	}
}
