Problem Statement  
A positive integer a is a proper factor of n if and only if n is a multiple of a and a does not equal 1 or n. You are given a int[] factors containing all the proper factors of some integer n. Return n.  
Definition  
 
Constraints  
  factors will contain between 1 and 50 elements, inclusive.  
  factors will be a valid set of proper factors of some number n, where n is between 2 and 1,000,000, inclusive.  
  All elements in factors will be distinct.  
Examples  
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