You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Christopher Taylor.

ASSISTANT: How can I help you?

USER: I planned to meet my cousin in DCA, can you please help me to book a flight ticket from PHL?

ASSISTANT: Sure, can you please tell your travelling dates?

USER: I planned to travel on 02/18 and 02/20.

ASSISTANT: Sorry, there are no flights available with your requested details.

USER: Ok, no problem. Thank you for your time.

ASSISTANT: Thank you and have a nice day.