Problem Statement  
We have some coins on the table. Each coin is characterized by its size. We want to arrange these coins into successive piles so that the following hold:
You will be given a int[] sizes, each element of which represents the size of a coin on the table. Return the maximal number of piles that we can organize according to the given rules. Each coin should be used in exactly one pile.  
Definition  
 
Notes  
  The maximal element of sizes will be unique, so it's always possible to form at least one pile.  
Constraints  
  sizes will have between 1 and 50 elements, inclusive.  
  Each element of sizes will be between 1 and 1000, inclusive.  
  The maximal element of sizes will be unique.  
Examples  
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