#include <bits/stdc++.h>

//const static double	de_PI	= 3.14159265358979323846;
//const static int	de_MOD	= 1000000007;
//const static int	de_MAX	= 999999999;
//const static int	de_MIN = -999999999;

int main(void) {

	//std::ifstream in("123.txt");	std::cin.rdbuf(in.rdbuf());

	int D = 0;
	std::cin >> D;

	if (D <= 3) {
		std::cout << 0 << std::endl;
		return 0;
	}

	if (D % 2 == 1) {
		D -= 1;
	}

	std::cout << std::setprecision(20) << D / 4 * ceil(D / 4.0) << std::endl;
	return 0;
}