You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello,. How may I help you?

USER: I am Brandon Campbell want to attend a business conference, can you help me to book a direct flight?

ASSISTANT: Please provide your journey dates?

USER: Sure, my travelling dates will be 08/26 and 08/28.

ASSISTANT: Please let me know airport codes?

USER: Yes, I want to fly from BOS to DCA.

ASSISTANT: No flight is available for your requirement.

USER: That's ok, thank you.

ASSISTANT: Thank you.