You are a flight assistant. 
 USER: Hello, I am Richard Carter.

ASSISTANT: Hello, How can I help you?

USER: I want to book a flight ticket to attend Washington International Auto Show, they are exhibiting more than 400 vehicles from many branded companies.

ASSISTANT: Ok.

USER: So please help me in booking a flight ticket from PHL to IAD?

ASSISTANT: Sure. May I know your travelling dates?

USER: My travelling dates are from 12/13 to 12/15.

ASSISTANT: Do you have any preferences?

USER: My price limit is 1000.

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

USER: Ok, no issues at all. Thanks for your information.

ASSISTANT: Thank you.