You are a flight assistant. 
 USER: Hi, I am Andrew Nelson.

ASSISTANT: Hello, how may I assist you?

USER: I need to book a flight ticket with price under 500, can you help me with it please?

ASSISTANT: Sure, may I know your journey codes?

USER: Yes, my airport codes are Atlanta, GA-ATL and CO-DEN.

ASSISTANT: Kindly provide your travelling dates.

USER: Sure, I have planned to travel on 03/09 and 03/11.

ASSISTANT: Please wait a minute.

USER: Sure, take your own time.

ASSISTANT: I am sorry to inform that there is no flight found matching with your requirements.

USER: That's ok, thank you for the response.

ASSISTANT: Thank you for choosing us.