numUnique

  Write a method called numUnique that takes three
   integers as parameters and that returns the number of unique integers among
   the three.  For example, if the following call is made:

        numUnique(18, 3, 4)

   the method should return 3 because the parameters represent 3 different
   numbers (the values 18, 3 and 4).  By contrast, the following call:

        numUnique(6, 6, 6)

   would return 1 because there is only 1 unique number among the three
   parameters (the value 6).  The values passed to your method might appear in
   any order whatsoever, so you cannot assume that duplicate values would
   appear together.  For example, if the following call is made:

        numUnique(7, 31, 7)

   the method should return 2 because there are 2 unique numbers among the
   parameters (the values 7 and 31).