Regular Expressions: Matching specific characters

Problem:

Create a regular expression that matches the following words "can" , "man" , "fan" ; those words shouldn't be followed "dan" , "ran" , "pan".

Output:

Solution:

Now this could be solved in many ways; the easiest and laziest way to solve this regular expression would be simply using this:

can|man|fan

Now, this sounds too mediocre; at least for me! I would prefer to solve it like this:

[cmf]an

As you see, regular expressions analyzes stuff character-by-character. So first you tell the regular expression to only match either 'c', 'm' or 'f' as a first character. Then add 'an' to the rest; which works.

Alternatively, you could use:

[^drp]an