This is such an interesting puzzle!  Looks like anyone should be able to solve it minutes, since its only 5 pieces.  Yet, it is SO much more difficult than it first appears!   My wife, reasonably good at puzzles, worked on it for hours and finally gave up....  It makes a fantastic desk or coffee table puzzle as people will want to try it and tend to get pulled into the puzzle, not wanting to give up.  You can attempt it in seconds and always seem to get close....