You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: Myself Mary Martin. I am looking for a flight from DEN to IAD, can you please help me in booking a flight ticket?

ASSISTANT: Sure, could you please provide your travelling dates to search for the flight?

USER: My travelling dates are May 28 and May 30.

ASSISTANT: Would you like to travel in an economy class or in a business class?

USER: I am comfortable with any class.

ASSISTANT:  Is there any another specifications on your trip, so that I can arrange like that only.

USER: I would to depart in evening.

ASSISTANT:  We regret to inform you that there are no flights moving to your region with your planned dates.

USER: That's ok, thank you for checking.

ASSISTANT: Welcome, have a nice day.