You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you at this moment?

USER: I am Margaret Lewis. I want to book a flight ticket to Philadelphia PHL, help me in booking my flight ticket from Denver DEN.

ASSISTANT: Sure, I will help you with this. Can you please share your journey dates?

USER: My journey dates will be Apr 15 to Apr 17.

ASSISTANT: May I know your price limit for this trip?

USER: I can spend up to 500 for my reservation.

ASSISTANT: Wait a moment please.

USER: Sure.

ASSISTANT: Margaret Lewis, there are no flight services available on this route on your provided dates.

USER: Its ok, thank you for your information.

ASSISTANT: Thank you for contacting us.