#include <iostream>
using namespace std;

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    int D, A = 0;
    cin >> D;
    if (D >= 4) {
        int hd = D / 2;
        A = (hd/2) * (hd-hd/2);
    }

    cout << A << endl;

    return 0;
}