You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I am Anthony Parker want to visit Denver, can you book a ticket within the fare of 200?

ASSISTANT: Sure, I will help you in booking the flight ticket with airfare of 200. Please, share me your location airport codes?

USER: Yes, I would like to travel from PHL to DEN.

ASSISTANT: Kindly, provide me your travel dates to check the flight in your way?

USER: Sure, my travelling dates will be 08/07 and 08/09.

ASSISTANT: Everything is noted, please wait a moment let you know the best flight with your preference.

USER: Ok.

ASSISTANT: Here I didn't find any flight in your route, all were sold out yet the moment.

USER: That's fine, thank you.

ASSISTANT: Sorry for the trouble. Thank you for reaching us.