#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint1000000007;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 100000000000000000


int main(){
	
	long long D;
	cin>>D;
	
	D /= 2;
	
	cout<<(D/2) * ((D+1)/2)<<endl;
	
	return 0;
}