You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am David Moore.

ASSISTANT: How may I assist you now?

USER: Can you please help me in booking a flight ticket from DCA t o IAH?

ASSISTANT: David Moore, may I know your travelling dates?

USER: I would like to travel on Sept 30 and return on Oct 2.

ASSISTANT: Do you need a connecting flight?

USER: Yes, I need connecting flight.

ASSISTANT: Sorry to inform you, there are no flights available for your journey.

USER: No problem, thank you for your kind service.

ASSISTANT: Thank you for approaching our agency. Have a nice day.