/* Check cf5-opt.vim defs.
VIM: let g:lcppflags="-std=c++11 -O2 -pthread"
VIM: let g:wcppflags="/O2 /EHsc /DWIN32"
*/
#include <iostream>

/*
Sum square difference
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.

Solution:
25164150
 */

int main ( void )
{
	const long long n = 100;
	long long s = n*(n+1)/2;
	s*=s;
	for ( long long i = 1; i <= n; ++i )
		s-=i*i;
	std::cout << s << std::endl;

	return 0;
}

