You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Gregory King here.

ASSISTANT: How may I help you?

USER: Please help me out in booking the ticket from IAD to DEN.

ASSISTANT: Sure, I am happy to help you. May I know your travel dates?

USER: My trip dates will be May 26 to May 28.

ASSISTANT: Ok, may I know your class preference?

USER: I am ok with the both classes.

ASSISTANT: Ok, please provide me your departure and arrival time?

USER: My depart time must be in the evening.

ASSISTANT: Ok, please wait for a while.

USER: Ok.

ASSISTANT: There is a flight available in Southwest airlines as per your requirements and the ticket fare is 200 only. Can I book the ticket for you?

USER: Please proceed.

ASSISTANT: Your ticket is booked in economy class. Flight departure time is at 2:00AM and arrival time is at 8:00AM.

USER: Thank you.

ASSISTANT: You are welcome.