You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may assist you?

USER: I need to book a ticket from LAS to SFO.

ASSISTANT: Sure, I am happy to help you. Please let me know your travelling dates.

USER: Departure is by May, 30 and return date is June, 1.

ASSISTANT: Do you prefer any lay by in between journey?

USER: I would prefer direct flight.

ASSISTANT: Are there any other specifications for you?

USER: I would like to depart in the evening time.

ASSISTANT: Can I have your good name?

USER: My name is Nicholas Wright.

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

USER: Thanks.