You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: I am heading from Washington, DC - IAD to attend a international conference at Philadelphia, PA - PHL. Can you help me with it?

ASSISTANT: Sure. May I know your travelling dates?

USER: They are planned to be on 04/28 and 04/30.

ASSISTANT: May I know your good name?

USER: My name is Mark Hill.

ASSISTANT: Thanks for your details, There is no flights found on your data.

USER: It's ok, thank you for the information.

ASSISTANT: Thank you.