You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I assist you?

USER: Book a ticket with the name of John Smith to Washington, DCA from Chicago, ORD.

ASSISTANT: Sure, Please help me with your travel dates.

USER: I have to fly on 04/23 to attend the interview. And return on 04/25.

ASSISTANT: Please wait a second.

USER: Sure.

ASSISTANT: Sorry, No flights found with your chosen dates.

USER: Not a issue. Thank you for aiding me.

ASSISTANT: Thank you for opting us.