You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

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

ASSISTANT: Sure, may I know your trip dates?

USER: I would like to depart on July 30 and return on Aug 01.

ASSISTANT: Do you have any other requirements?

USER: I prefer only direct flight for my journey.

ASSISTANT: Ok, may I know your name please?

USER: Myself Robert Harris.

ASSISTANT: Sorry Robert, there is no flight available on these dates.

USER: It's ok, thank you for sharing the information.

ASSISTANT: Most welcome.