You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: William King here.

ASSISTANT: How may I assist you?

USER: I have to attend a cultural event at PHL, can you help me to book a flight ticket from DEN?

ASSISTANT: Yes, can you tell me your travelling dates?

USER: I am planning to move on 11 May and return on 13 May.

ASSISTANT: Give me a moment.

USER: Sure.

ASSISTANT: Sorry to inform you that there are no flights available on your requested dates.

USER: That's ok, thank you for giving information.

ASSISTANT: Thank you for contacting us.