#include<bits/stdc++.h>
using namespace std;
int main() {
    int n;
    cin >> n;
    if(n % 2 == 1) {
        n = (n + 1) / 2;
        cout << n*n << endl;
    } else {
        n /= 2;
        cout << n*n << endl;
    }
    return 0;
}