The conversation between human and AI assistant.
[|Human|] Generate a 3 letter usernames with the following format: [first letter] + [random letter] + [last letter].
[|AI|] "Aal" could be one of many potential three-letter usernames which respects the specified format.
[|Human|] 
Generate a 3 letter usernames with the following format: [first letter] + [random letter] + [last letter].