You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you?

USER: I need to book a flight ticket.

ASSISTANT: Sure , could you please provide your journey information?

USER: Sure, My name is Lisa Nelson. I need to travel from CA-SFO to CO-DEN. Departure date is Apr/19 to Apr/21.

ASSISTANT: OK, please wait a moment I will check and get back to you.

USER: OK.

ASSISTANT: Sorry, there is no flights found on your details.

USER: OK.Thanks for your information.

ASSISTANT: Thank you, have a nice day.