#include <bits/stdc++.h>
#define REP(i, a, n) for(int i=a; i<n; i++)
#define RREP(i, a, n) for(int i=n-1; i>=a; i--)
using namespace std;

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

    if(d<4){
        cout<<0<<endl;
        return 0;
    }
    d/=2;

    if(d%2==1){
        cout<<(d/2)*(d-d/2)<<endl;
    }
    else{
        cout<<(d/2)*(d/2)<<endl;
    }
    return 0;
}