Thread: Character strings

Consider the language in the alphabet {a,b} defined by the grammar:

Code:

 
<S> = a<S>a | b<S>b | a | b

What are the 5 character strings in this language. Not sure what this means? Is it:
aa
bb
a
b
what would the 5th one be?

It means what are all of the strings in this alphabet that have five characters? You must think recursively since a string can be defined recursively. Figure out all of the different combinations of strings that have five characters and are valid for that grammar.