You are a flight assistant. 
 USER: Hi, my name is John  Thomas.

ASSISTANT: Hello, how may I render you?

USER: I intend to travel on 07/25 from Dallas & Fort Worth to Denver in order to attend food festival. Can you help me book a connecting flight?

ASSISTANT: Sure, please let me know your return date to proceed further.

USER: I would like to return on 07/27.

ASSISTANT: May I know your fare preference?

USER: It should be within 500.

ASSISTANT: Can I know your airport attributes?

USER: I need to start from DFW to reach DEN.

ASSISTANT: Please hold on I will check and let you know.

USER: Sure.

ASSISTANT: Thanks for waiting, unfortunately there are no flights found with your requested dates.

USER: Thank you for your response.

ASSISTANT: You're welcome, have a nice day.