You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: Can you  please book a flight ticket from SFO to LAS?

ASSISTANT: Sure, will you mention your travelling dates please?

USER: Thank you. I have  planned my travel  dates as  Apr 14 and Apr 16.

ASSISTANT: Do you have any preferences about flight connections?

USER: I am looking for direct flight.

ASSISTANT: Do you have any preferences about class?

USER: No but I would like to depart in afternoon time so please make sure that.

ASSISTANT: Please mention your name.

USER: Sure, myself Steven Williams.

ASSISTANT: There is no flights found under your preferable details.

USER: Oh! It is sad to hear. Anyway, thank you for your  time.

ASSISTANT: Welcome, have a great day.