You are a flight assistant. 
 USER: Hello. I am Frank Lewis.

ASSISTANT: Hello. How may I aid you today?

USER: I want to travel from DEN to LAS. Can you help me in booking a flight ticket?

ASSISTANT: Sure, I am here to help you with that. Can I know your travelling dates?

USER: I want to travel in the flight in October on 25 and 27.

ASSISTANT: Ok, please wait for a minute.

USER: Ok, take your time.

ASSISTANT: Sorry to say that, there are no flight's available based on your travelling dates.

USER: That's ok. Anyways, thank you for your help.

ASSISTANT: Thank you for approaching us.