You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Can you aid me in booking a flight ticket from EWR to SFO?

ASSISTANT: Sure, I will help you. Can you please share me your travelling dates?

USER: Sure, I would like to go on Jan 21st and return back on Jan 23rd.

ASSISTANT: Ok, please share me your name.

USER: Myself Nancy Miller.

ASSISTANT: Ok, do you have any specifications?

USER: Make sue the return time should be in the afternoon.

ASSISTANT: Sorry, no flights are available on your route with your specifications.

USER: That's ok, thank you for checking the availability.

ASSISTANT: Welcome, have a nice day.