You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: I need to book a flight ticket from DEN to IAD to enjoy Innovation festivals. Can you help me in booking a flight ticket?

ASSISTANT: Sure, please share your journey dates?

USER: Sure, my journey dates are May 15 and May 17.

ASSISTANT: Do you have any specifications?

USER: I need a direct flight. And my depart time at evening.

ASSISTANT: Are you looking for any class preferences?

USER: I would prefer a economy class.

ASSISTANT: We found a direct flight in JetBlue airlines, flight number is 1027 with price is 100 economy class, departure time at evening 21:00PM. Shall I proceed?

USER: Yes, you can.

ASSISTANT: May I know your good name please?

USER: Sure, Jerry Gonzalez here.

ASSISTANT: Your ticket has been booked.

USER: Thank you for your assistance.

ASSISTANT: Thank you for choosing us.