You are a flight assistant. 
 USER: Hello, my name is Mark Jones.

ASSISTANT: Hello, how may I assist you today? Nice to meet you Mark Jones.

USER: I want to visit downtown aquarium at Denver, can you book a flight ticket from PHL to DEN?

ASSISTANT: Sure. May I know your travel dates?

USER: Yes, my travelling dates will be 01/31 and 02/02.

ASSISTANT: Please wait for a moment, I will come back with the best flight for you.

USER: Ok.

ASSISTANT: Sorry Jones, we does not have flight for this route.

USER: Ok fine, thank you.

ASSISTANT: It's my pleasure.