#include <algorithm>
#include <iostream>
#include <vector>
using namespace std;

int main() {
    int n; cin >> n;
    n /= 2;
    if (n % 2) cout << n / 2 * (n + 1) / 2 << endl;
    else cout << n / 2 * n / 2 << endl;
    return 0;
}