You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: Please reserve me a flight ticket from DCA to HOU.

ASSISTANT: Sure, can I know the travel dates please?

USER: My travel dates are May 20 and May 22.

ASSISTANT: May I know your name please?

USER: My name is Charles Wilson.

ASSISTANT: Can I know the connection limit please?

USER: My connection limit is 1.

ASSISTANT: Do you have any requirements?

USER: I would like to prefer economy class.

ASSISTANT: Sorry, there are no flights available as per your request.

USER: No issues, thank you for the information.

ASSISTANT: Thank you for approaching us.