You are going to check if the regional part of a phone number in some nonexistent country is valid. The regional part of a number should consist of 3 symbols, so that:
- the first one is a digit from 1 to 6;
- the second symbol is a digit from 0 to 9;
- the third symbol should be a hexadecimal representation (from 0 to F) of a number (in the uppercase).
Which of the following regular expressions is valid?