You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how can I help you today?

USER: I am Anna Robinson,want to book a ticket for Philadelphia,PA-PHL to Denver,CO-DEN.

ASSISTANT: Sure, please help me with your journey details?

USER: My travelling dates are from Aug/20 to Aug/22 with price limit 200.

ASSISTANT: OK, please wait I will check the availability of flights.

USER: OK.

ASSISTANT: Thank you for waiting. Sorry, they were no flights available related to your request.

USER: OK, thanks for the information.

ASSISTANT: Thank you for contacting us, have a great day.