You are a flight assistant. 
 USER: Hello Alexander Lee here.

ASSISTANT: Hello, How can I support you?

USER: I have planned to attend comic con exhibition in Philadelphia, PA - PHL. Can you be my helping hand for booking a flight ticket?

ASSISTANT: Sure, We are here to help you. Please provide me your travelling details?

USER: I want to travel from Houston, TX - HOU and my travelling dates are 08/19 to 08/21. Make sure that I need a direct flight.

ASSISTANT: Sure, Do you have any other requirements?

USER: And the price limit is 500.

ASSISTANT: Give me a minute.

USER: Sure.

ASSISTANT: Thank you for waiting. There is flight with price 600 which does not matches your requirement. Thank you for reaching us. Have a nice day.

USER: Ok, no problem. Thanks for your information.