#include <bits/stdc++.h>
using namespace std;

signed main(){
  int D; cin >> D;
  if( D < 4 ) cout << 0 << endl, exit( 0 );
  D /= 2;
  int f = D / 2;
  if( D == 2 * f + 1 )
    cout << f * ( f + 1 ) << endl;
  else
    cout << f * f << endl;
  return 0;
}