You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you?

USER: I am Dorothy Adams. Can you please book me a ticket from DCA to LAX?

ASSISTANT: sure, please provide me travelling dates.

USER: I would like to leave between 06/18 and 06/20.

ASSISTANT: Sorry, there are no flights at this moment.

USER: Ok, no problem. Thank you so much.

ASSISTANT: Have a good day.