You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello, How can I amend you?

USER: I need to attend a family trip at Seattle, please book a direct flight with price within 500.

ASSISTANT: Sure, I am happy to help you. Kindly mention your travelling dates?

USER: Depart date on 05/18 and return date on 05/20.

ASSISTANT: Can you please provide me your airport abbreviates?

USER: I want to fly from DC- IAD to WA- SEA.

ASSISTANT: May I know your good name?

USER: I am Daniel Perez.

ASSISTANT: Thanks for your name. Please wait a moment, I will check and revert you.

USER: Ok.

ASSISTANT: We are very sorry to notify you that there is no flight found based on your details.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for choosing us.