Problem Statement  
You are going to stick the number of your room on the door. The shop near your house suggests wonderful sets of plastic digits. Each set contains exactly ten digits  one of each digit between 0 and 9, inclusive. Return the number of sets required to write your room number. Note that 6 can be used as 9 and vice versa.  
Definition  
 
Constraints  
  roomNumber will be between 1 and 1,000,000, inclusive.  
Examples  
0)  
 
1)  
 
2)  
 
3)  
