You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I support you?

USER: I want to book a ticket from SFO to DCA, can you help me?

ASSISTANT: Please let me know your preferred dates of trip.

USER: My travel dates are 06/21 and 06/23.

ASSISTANT: Give me a minute.

USER: Ok.

ASSISTANT: May I know your name?

USER: Myself Dorothy Garcia.

ASSISTANT: Sorry Garcia, no flight is available.

USER: No problem, thanks for checking.

ASSISTANT: You are welcome, have a great day.