Problem Statement  
A doll vendor has just received a shipment of dolls from the factory. Their sizes are given in the int[] dollSizes. The vendor can only sell dolls in sets of two such that one doll is K times as large as the other. What is the maximum number of sets that the vendor can assemble? Each doll can only be used in a single set.  
Definition  
 
Constraints  
  dollSizes will contain between 1 and 50 elements, inclusive.  
  Each element in dollSizes will be between 1 and 1000000, inclusive.  
  K will be between 1 and 25, inclusive  
Examples  
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