You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Charles Robinson here.

ASSISTANT: Charles, how may I help you?

USER: I'm planning a round trip in IAD, can you please help me in booking the ticket?

ASSISTANT: Sure, please share your airport codes.

USER: Sure, my departure date is 06/02 and return date is 06/04.

ASSISTANT: Please hold on for a while.

USER: Sure, take your time.

ASSISTANT: Sorry, no flight is available on your route.

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

ASSISTANT: Thank you for choosing us.