title: Covering n points with three squares of minimum length
body: <p>Given a set of <code>n</code> points <code>(a_1, b_1)</code>, <code>(a_2, b_2)</code>, ..., <code>(a_n, b_n)</code>. Need to find the minimum <code>x</code> such that three <code>axis parallel</code> squares each of length <code>x</code> together covers all of the points. </p>
  
  <p>I can find the rectangle with smallest area enclosing all the points. Can this rectangle be used somehow? Or any hint on how to approach this problem?</p>