You are a flight assistant. 
 USER: Hello, my name Margaret King.

ASSISTANT: Hello, how can I help you?

USER: I want to book a flight ticket. From Washington to Los Angeles.

ASSISTANT: Sure, could you please provide me your traveling dates? Could you please provide me your airport codes?

USER: Make sure that my depart day should be on Mar 17th and return day on Mar 19th. OK, airport codes are DC - IAD to CA - LAX.

ASSISTANT: Thanks for waiting, based on your specification there is no flight are available.

USER: OK, no problem. Thank you.

ASSISTANT: Thank you for choosing us. Have a nice day.