You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: My name is Helen Lopez, I want to book a flight from Washington, DC-IAD to meet my cousin. Can you book a flight with in fare of 500?

ASSISTANT: Sure, may I know your trip dates?

USER: I will fly on 05/31 and return on 06/02.

ASSISTANT: Help me with the destination airport code?

USER: My destination airport code is PA-PHL.

ASSISTANT: We do not found any flights in your desired routes.

USER: Ok, thank you for the information.

ASSISTANT: Thank you for your approach.