You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: Myself Charles Wilson, I need to attend a metting at Denver.Could you help me by booking a ticket?

ASSISTANT: Sure, can I know the travel dates please?

USER: I am willing to travel on 05/20 and again I will retrive on 05/22.

ASSISTANT: Could you please provide the airport codes?

USER: My departure and destination airport codes are ATL to DEN.

ASSISTANT: Sorry, there are no flights available on your route.

USER: Not a big deal, anyway thank you very much for your service.

ASSISTANT: Thank you for approaching us.