You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: My name is Angela Williams, can you help me to book a flight ticket from DEN to JFK?

ASSISTANT: Sure, may I know your planned travel dates?

USER: Ok, please book for the dates Apr 16th and 18 respectively.

ASSISTANT: Do you have any specifications?

USER: Ok, please book a connecting flight which depart during afternoon.

ASSISTANT: Sorry, there are no flights available for your desired dates.

USER: Thank you for assisting me.

ASSISTANT: Thank you for reaching us.

USER: That is ok, I will book next week.