#include <bits/stdc++.h>
#define p(s) cout<<(s)<<endl
using namespace std;

int main(){
	int D,ans=0;
	cin>>D;
	D/=2;
	if(D%2==0) ans=(D/2)*(D/2);
	else ans=(D/2+1)*(D/2);
	p(ans);
	return 0;
}