You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you?

USER: This is Cynthia Martin, can you help me to book a flight ticket from DCA to HOU?

ASSISTANT: Sure, can you share your trip dates?

USER: My preferable journey dates are Oct 19 and Oct 21.

ASSISTANT: Do you have any preferences?

USER: I would like to depart in the afternoon time.

ASSISTANT: Sorry, there is no flight on your given dates.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for reaching us.