Problem Statement  
A number is called 2digitprime if using each of its digits at most once, we can make a prime number containing exactly 2 digits (with no leading zeros). For example, 153 is 2digitprime because we can use its digits to make 13, which is a prime number with 2 digits (note that we can also make 53 and 31). Given ints a and b, return the number of 2digitprime numbers between a and b, inclusive. See examples for further clarification.  
Definition  
 
Constraints  
  b will be between 10 and 100000, inclusive.  
  a will be between 10 and b, inclusive.  
Examples  
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