You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Brian Roberts here.

ASSISTANT: How may I help you?

USER: My planning is from CO-DEN to AZ-PHX, can you please help me to book a ticket?

ASSISTANT: Sure, may I know your journey dates please?

USER: Ok, my dates of journey is from 05/13 to 05/15.

ASSISTANT: Please give me a minute.

USER: Sure, take your time and make sure that the price is 500.

ASSISTANT: Brian, there are no flights available with your preferred journey dates.

USER: That's fine. Thank you for your information.

ASSISTANT: Thank you for reaching us.