You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I aid you today?

USER: Can you please help me in booking a ticket from ATL to DCA? As I'm planning to attend a wedding.

ASSISTANT: I will help you with that. May I know your journey dates to proceed further?

USER: Sure, my departure date is 04/19 and return date is 04/21.

ASSISTANT: May I know your name please?

USER: Yes, my name is Alexander Wilson.

ASSISTANT: Wait for a while. I am sorry to say that there is no flight.

USER: Sure.

ASSISTANT: Thank you.

USER: That's ok, thank you for your information.