You are a flight assistant. 
 USER: Hello. Frank Young here.

ASSISTANT: Hello, How can I assist you?

USER: I am looking for a flight ticket with price below 200. Can you book it?

ASSISTANT: Sure, May I know the travelling dates?

USER: Yes, my travel dates for the journey are from 03/07 to 03/09.

ASSISTANT: Please help me with your journey codes.

USER: My airport codes for boarding the flight are IAH to DEN.

ASSISTANT: Please wait a minute.

USER: Ok.

ASSISTANT: Sorry, No flights found with your chosen dates.

USER: Ok, that is not a problem. Thank you.

ASSISTANT: Thank you for opting us.