#include <bits/stdc++.h>
#include <atcoder/all>


using namespace std;
using namespace atcoder;
#define rep(i,m,n,k) for (int i = (int)(m); i < (int)(n); i += (int)(k))
#define rrep(i,m,n,k) for (int i = (int)(m); i > (int)(n); i += (int)(k))
#define ll long long
#define list(T,A,N) vector<T> A(N);for(int i=0;i<(int)(N);i++){cin >> A[i];}
 


int main(){
    
    ll D;
    cin >> D;
    if (D<=3){
        cout << 0 << endl;
        return 0;
    }
    ll M;
    M = D/2;
    cout << (M/2)*(M - M/2) << endl;
    return 0;
}