You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I would like to visit San Francisco for site seeing, please help me in booking a ticket from ORD to SFO.

ASSISTANT: May I know your desired travel dates please?

USER: My planned travel dates are on Jan 27 and Jan 29.

ASSISTANT: Do you have any specifications?

USER: I would like to return in the evening.

ASSISTANT: May I know your name please?

USER: My name is Joshua Campbell.

ASSISTANT: Sorry to say, there is no flight on your desired travel dates.

USER: Ok, no issues. Thank you for your information.

ASSISTANT: Thank you for opting us.