Problem Statement 
 You are given two Strings, number and digits. Each String contains only digits between 1 and 9, inclusive. For each occurrence of a digit in digits, you must remove a single occurrence of that digit from number. Your goal is to end up with the largest possible remaining number after all the necessary digits are removed. Return this number as a String. 

Definition 
 Class:  RemovingDigits  Method:  maxNumber  Parameters:  String, String  Returns:  String  Method signature:  String maxNumber(String number, String digits)  (be sure your method is public) 




Constraints 
  number will contain between 1 and 50 characters, inclusive. 
  digits will contain between 0 and n1 characters, inclusive, where n is the number of characters in number. 
  Each character in number and digits will be a nonzero digit ('1''9'). 
  The number of occurrences of each digit in number will be greater than or equal to the number of occurrences of that digit in digits. 

Examples 
0)  
  Returns: "24"  If we remove the digits '5', '3', '1' we get the number 24. 


1)  
  Returns: "52"  There are two choices. We can either get a "25" or a "52". The largest is "52". 


2)  
  Returns: "654321"  Removing the first half of our number gives us the maximum result. 


3)  
  Returns: "654321"  Removing the last half of our number gives us the maximum result. 


4)  
 "2654982765982365"  "2345978" 
 Returns: "698265265"  
