import std.algorithm, std.array, std.container, std.range;
import std.string, std.conv, std.math, std.random;
import std.stdio, std.typecons;

void main()
{
  auto d = readln.chomp.to!int;
  auto e = d / 2;
  auto f = e / 2;
  writeln(f * (e - f));
}