#include <iostream>
using namespace std;
 
int main(){
	int D;
	cin >> D;
	
	int w = D / 4;
	int m = D % 4;
 
	if(m >= 2){
		cout << w * (w + 1) << endl;
	} else {
		cout << w * w << endl;
	}
 
	return 0;
}