#include <iostream>
using namespace std;

int main(void)
{
	int D;
	cin >> D;

	if(D<4) {
		cout << 0 << endl;
	} else {
		if(D%4 >= 2) {
			cout << (D/4) * (D/4+1) << endl;
		} else {
			cout << (D/4) * (D/4);
		}
	}

	return 0;
}