You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I want to book a ticket from New York, JFK and Denver, DEN to go for Sports festival. Can you please help me for booking?

ASSISTANT: Sure, may I know your travel dates?

USER: My scheduled dates are Aug 12 and Aug 14.

ASSISTANT: Do you have any specific time for leave and return?

USER: My depart time is afternoon.

ASSISTANT: Please share me your name.

USER: I am Frank Hill.

ASSISTANT: Sorry, there is no flight at this moment.

USER: Ok, Thank you.

ASSISTANT: Thank you.