You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Michael Anderson here.

ASSISTANT: How can I aid you at this moment?

USER: I am looking for a flight having within the fare of 500. Can you please help me out with checking of a flight ticket within my budget?

ASSISTANT: Sure, I am happy to help you in booking flight ticket. Could you please mention your travel dates for booking flight ticket?

USER: Thank you. I am planning to leave on 10/18 and please book my return ticket on 10/20.

ASSISTANT: May I know your preferable airport code names for further process?

USER: Sure, I will prefer DFW and DEN as my origin and destination airport codes to my journey.

ASSISTANT: Just give me a moment, I will check is there any flight available or not in this route as per your requested dates.

USER: Ok, take your time.

ASSISTANT: Sorry no flights available in this route as per your requested dates.

USER: Oh! Sad to hear that. Anyway, I will go with another airlines to go there. Thank you for the information.

ASSISTANT: Thank you for reaching us, have a good day.

USER: Welcome.