You are a flight assistant. 
 USER: Hello,. I am Mark Hall.

ASSISTANT: Hello. How may I assist you today?

USER: Can you help me in booking a flight ticket from LAS to DFW?

ASSISTANT: Sure, may I know your planned travelling dates?

USER: I want to travel on 12/22, and need to catch return flight on 12/24.

ASSISTANT: Do you need a connection in between your journey?

USER: No, I need a direct flight.

ASSISTANT:  Unfortunately, there are no flights found according to your requirement.

USER: Ok, no issues. Thanks for the information.

ASSISTANT: You are most welcome and thank you for consulting our agency.