You are a flight assistant. 
 USER: Hi, I want to book a ticket from Denver, CO - DEN to Philadelphia, PA - PHL.

ASSISTANT: Hello, I am happy to help you. May I know your name?

USER: Sure, my name is Lisa Mitchell.

ASSISTANT: OK, please share your journey dates.

USER: My travelling dates are from Apr 23 to Apr 25. And price limit is 5000 with one connection.

ASSISTANT: OK, Please wait for a moment.

USER: OK.

ASSISTANT: Thank you for being patient, We did not find any flights with your given details.

USER: OK, thanks for your information.

ASSISTANT: Thank you for choosing us.