#include <iostream>
using namespace std;

int main() {
	int D;
	cin >> D;
	
	if(D < 4){
		cout << 0 << endl;
		return 0;
	}
	
	int A;
	
	if(D%2)D--;
	if(D%4)A = (D/4)*(D/4+1);
	else A = (D*D)/16;
 
	cout << A << endl;
	return 0;
}