Problem Statement  
A web site for movie fans assigns a composite rating to each movie. Your task is to calculate the rating of a particular movie. Users of the site rate the movie on a scale of 0 to 100, inclusive. The lowCount lowest ratings and the highCount highest ratings are thrown away, and the composite rating is the average of the remaining individual ratings. Given the user ratings in a int[] marks, together with lowCount and highCount, return the rating of the movie.  
Definition  
 
Notes  
  A return value with either an absolute or relative error of less than 1.0E9 is considered correct.  
Constraints  
  marks will contain between 1 and 50 elements, inclusive.  
  Each element of marks will be between 0 and 100, inclusive.  
  lowCount and highCount will be between 0 and 50, inclusive.  
  lowCount+highCount will be strictly less than the number of elements in marks.  
Examples  
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