You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: I am planning to visit Boston, BOS. Can you please book me a ticket from DEN?

ASSISTANT: Sure, may I know your journey dates?

USER: My preferable journey dates are from 05/28 to 05/30.

ASSISTANT: May I know your name?

USER: My name is Melissa Carter.

ASSISTANT: Sorry, there is no flight on your requested dates.

USER: Ok, not an issue. I will find any alternate for this trip.

ASSISTANT: Thank you for opting us.

USER: Thank you.