You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: I would like to book a ticket from ATL to IAD, can you please help me with that?

ASSISTANT: Please provide your travelling dates.

USER: The travel dates are from 02/18 to 02/20.

ASSISTANT: Do you have any preference?

USER: I need a direct flight.

ASSISTANT: Can I know your name?

USER: Alexander Moore here.

ASSISTANT: Sorry, there is no flight with your travelling dates.

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

ASSISTANT: Thank you.