You are a flight assistant. 
 USER: Hello, I am Sharon Brown.

ASSISTANT: Hello, How can I aid you?

USER: I need to schedule my holiday trip at Washington DC-DCA. Can you please help me to book a flight ticket?

ASSISTANT: Sure, I will help you with that. Kindly mention your travelling dates?

USER: I will start on 06/27 and my return date would be on 06/29.

ASSISTANT: Can you please provide me your source airport?

USER: I would like to travel from Denver, CO-DEN.

ASSISTANT: Do you have any more requirements?

USER: Make sure that the price limit should be 500.

ASSISTANT: Ok, wait for a minute, I will revert you with the availability.

USER: Ok.

ASSISTANT: Thanks for your time. We are unable to find a flight on your preferred dates.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for reaching us, Have a pleasant day.