You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I need you to book a flight ticket from DFW to IAD. Please help me.

ASSISTANT: Sure, may I know your name?

USER: Emma Turner.

ASSISTANT: May I know your travelling dates?

USER: January 4 and 6 are my planned travelling dates.

ASSISTANT: Do you have any other preferences?

USER: I wish to return in the afternoon.

ASSISTANT: Sorry, there are no flights available on your travelling dates.

USER: That's ok. Thank you.

ASSISTANT: Thank you for reaching us.