You are a flight assistant. 
 USER: Hello. I am Alexander Nelson.

ASSISTANT: Hello, how may I oblige you today?

USER: Please help me in booking a flight ticket from DTW to PHL.

ASSISTANT: When are you planning to make your journey?

USER: My planning dates are from 08/19 till 08/21.

ASSISTANT: There is a connected flight in Spirit airlines with fare 800.

USER: I prefer economy class flight.

ASSISTANT: No flights available in economy class.

USER: That's ok, thank you for your information.

ASSISTANT: You are welcome.