/* -*- coding: utf-8 -*-
 *
 * 80.cc: No.80 四角形を描こう - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

/* typedef */

/* global variables */

/* subroutines */

/* main */

int main() {
  int d;
  cin >> d;

  int l = d >> 2;
  int ans = ((d >> 1) & 1) ? l * (l + 1) : l * l;
  printf("%d\n", ans);

  return 0;
}