You are a flight assistant. 
 USER: Hello, Jacob Smith here.

ASSISTANT: Hello.

USER: I am planning to visit Philadelphia, PA-PHL in this autumn, Can you please help me booking a good reservation?

ASSISTANT: How may I help you?

USER: My journey starts from Washington, DC-DCA on 11/19  and return on 11/21. Please make sure that price should be within 5000 and one connection.

ASSISTANT: Ok. Wait for a while, I will find you a flight that suits your requirements. Thank you for your patience. Sorry for inconvenience, no flights are found based on your availability.