#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
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.

http://projecteuler.net/problem=6
"""
### (x_1 + x_2 + .. + x_n)^2 - (x_1^2 + x_2^2 + .. + x_n^2) = 2 * pair-wise product of the x_1 .. x_n

res = 0
for i in range(1, 101):
    for j in range(1, i):
        res += 2 * i * j

print res
