#include <iostream>
#include <vector>
#include <array>
#include <algorithm>
#include <cmath>
#include <stack>
#include <queue>
#include <map>
#include <unordered_map>
#include <cassert>
#pragma GCC optimize("O3")
#pragma comment(linker, "STACK:36777216")
using namespace std;
using i64 = int64_t;
constexpr i64 MOD = 1e9 + 7;

int main() {
    i64 n;
    cin >> n;
    i64 t = n / 2;
    cout << t * t << endl;
}