#include <bits/stdc++.h> using namespace std; typedef long long ll; typedef pair<ll, ll> p_ll; template<class T> void debug(T itr1, T itr2) { auto now = itr1; while(now<itr2) { cout << *now << " "; now++; } cout << endl; } #define repr(i,from,to) for (int i=(int)from; i<(int)to; i++) #define all(vec) vec.begin(), vec.end() #define rep(i,N) repr(i,0,N) #define per(i,N) for (int i=(int)N-1; i>=0; i--) const ll MOD = pow(10,9)+7; const ll LLINF = pow(2,61)-1; const int INF = pow(2,30)-1; vector<ll> fac; void c_fac(int x=pow(10,6)+10) { fac.resize(x,true); rep(i,x) fac[i] = i ? (fac[i-1]*i)%MOD : 1; } ll inv(ll a, ll m=MOD) { ll b = m, x = 1, y = 0; while (b!=0) { int d = a/b; a -= b*d; swap(a,b); x -= y*d; swap(x,y); } return (x+m)%m; } ll nck(ll n, ll k) { return fac[n]*inv(fac[k]*fac[n-k]%MOD)%MOD; } ll gcd(ll a, ll b) { if (a<b) swap(a,b); return b==0 ? a : gcd(b, a%b); } ll lcm(ll a, ll b) { return a/gcd(a,b)*b; } int main() { ll D; cin >> D; D/=2; ll result = (D/2) * (D-D/2); cout << result << endl; return 0; }