title: box stacking in graph theory
body: <p>Please help me find a good solution for this problem.</p>
  
  <p>We have n boxes with 3 dimensions. We can orient them and we want to put them on top of another to have a maximun height. We can put a box on top of an other box, if 2 dimensions (width and lenght) are lower than the dimensions of the box below.</p>
  
  <p>For exapmle we have 3 dimensions w*D*h, we can show it in to (h*d,d*h,w*d,d*W,h*w,w*h)
  please help me to solve it in graph theory.
  in this problem we can not put(2*3)above(2*4) because it has the same width.so the 2 dimension shoud be smaller than the box</p>