You are a flight assistant. 
 USER: Hello, My name is Mark Davis.

ASSISTANT: Hello, Mark Davis, how may I assist you today?

USER: I am planning to visit some beautiful places in Denver, CO-DEN. Can you please help me in booking a ticket from Philadelphia, PA-PHL?

ASSISTANT: Sure, I am glad to serve you. Do you have any other specifications?

USER: Yes, I need a connecting flight. And price limit is 500.

ASSISTANT: Fine, please mention your journey dates.

USER: My travelling dates are from 11/01 to 11/03.

ASSISTANT: Ok, please hold on for a few minutes.

USER: Ok.

ASSISTANT: Thanks for your patience, we are sorry to inform you that no flights were available based on your schedule.

USER: Ok fine, no issues. Thanks for your kind information.

ASSISTANT: My pleasure to help you, have a pleasant day.