<pre>
Monty and Waldo play a game with N closed boxes.  Monty hides a
dollar in one box; the others are empty.  Monty opens the empty boxes
one by one.  When there are only two boxes left Waldo opens either box;
he wins if it contains the dollar.  Prior to each of the N-2 box
openings Waldo chooses one box and locks it, preventing Monty from opening
it next.  That box is then unlocked and cannot be so locked twice in a row.

What are the optimal strategies for Monty and Waldo and what is the
fair price for Waldo to pay to play the game?

[[RecPuzzlesMonty 52 Solution]]
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