#include <vector>
#include <queue>
#include <deque>
#include <stack>
#include <map>
#include <set>
#include <algorithm>
#include <functional>
#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <cctype>
#include <string>
#include <cstring>

using namespace std;

typedef long long ll;


int main() {
  int d;
  cin >> d;
  if (d%2) d--;
  d/=2;
  cout << max(0, max((d/2)*((d+1)/2), (d/2+1)*((d+1)/2-1))) << endl;
}