You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello, how can I serve you for the day?

USER: Please book a ticket from San Francisco, CA-SFO to Washington DC-DCA, for culture, heritage and folk festival. I'm Michelle Nelson.

ASSISTANT: Ok, when do you want start your journey?

USER: 01/19 is depart date and will return by 01/21.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: Sorry, there are no flight found.

USER: Thanks.

ASSISTANT: Thank you for choosing us.