You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Can You help me to book a flight ticket from LAS to PHX?

ASSISTANT: Sure, please provide your travel dates.

USER: My travel dates are Apr 20 and Apr 22.

ASSISTANT: Do you have any preferences?

USER: I would like to return back in the evening time.

ASSISTANT: May I know your name?

USER: My name is Charles Gonzalez.

ASSISTANT: Sorry, I did not find any flights for you.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for reaching us.