You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I am Stephanie Moore. Can you book a flight ticket from SEA to LAX?

ASSISTANT: Sure, may I know your travel dates?

USER: My planned travel dates are May, 19 and May, 21.

ASSISTANT: At what time do you like to travel?

USER: My depart time should be at evening.

ASSISTANT: Do you prefer economy or business class?

USER: I am comfortable with any class.

ASSISTANT: Sorry, there is no flight on your details.

USER: It's ok, not a problem. Thank you.

ASSISTANT: Thank you.