Problem Statement  
A cat and a rabbit are playing a simple number guessing game.
The cat chose two different positive integers X and Y.
He then told the rabbit several numbers.
One of those numbers was X + Y and another was X  Y.
The others were simply made up.
The rabbit thinks the cat prefers large numbers. Given a int[] hints containing the numbers the cat told the rabbit, return the largest possible value of X * Y.  
Definition  
 
Constraints  
  hints will contain between 2 and 50 elements, inclusive.  
  Each element of hints will be between 1 and 100, inclusive.  
  All elements of hints will be distinct.  
  There will exist at least one pair of positive integers (X, Y) such that both X + Y and X  Y are elements of hints.  
Examples  
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