You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Can you please help me to book a flight from IAD to DCA?

ASSISTANT: Sure, may I know your travelling dates?

USER: Sure, I want to travel on Sept 8 and need to return on Sept 10.

ASSISTANT: May I know your connection limit?

USER: I need a flight with single connection.

ASSISTANT: Do you have any other preferences?

USER: I prefer an normal-cost airline to travel.

ASSISTANT: May I know your name?

USER: My name is Richard Garcia.

ASSISTANT: Sorry, there are no flights available on your travelling us.

USER: Ok, no problem. Thank you for the information.

ASSISTANT: Thank you for choosing us.