1145141919380

#include <iostream>
using namespace std;

int main() {
	long long n, m;
	cin >> m;
	long long num = 0;
	for (long long i = 1; i <= m; ++i) {
		if (i % 2 == 0) {
			num += i*i;
		}
	}
	cout << num;
}