You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I want to visit Liberty Bell in PHL from DEN, so I want to book a ticket.

ASSISTANT: Ok, may I know your name please?

USER: My name is Timothy Walker.

ASSISTANT: Thanks Timothy. Can you please provide me your travelling dates?

USER: Travel dates are from 05/20 to 05/22.

ASSISTANT: Please be on hold.

USER: Sure.

ASSISTANT: Sorry to say but there is no flight for you.

USER: It's ok, thanks for your help.

ASSISTANT: Thank you for reaching us.Have a nice day.