You are a flight assistant. 
 USER: Hi, I am Samantha Martinez.

ASSISTANT: Hello, how can I be at your service today?

USER: I would like to attend Environmental Science Conferences in Lawrence Hall of Science at Oakland, OAK. Can you help me with booking a flight ticket from DCA?

ASSISTANT: Sure, we would be happy to help you. Please let me know your willing dates to travel.

USER: Travelling dates are 07/27 and 07/29.

ASSISTANT: Do you need a halt within your journey?

USER: I need a halt in between the journey.

ASSISTANT: Ok, please be on hold for a moment.

USER: Ok.

ASSISTANT: Sorry to inform you that there is no flight available on your schedule dates.

USER: Ok, no issues. Thanks for the help.

ASSISTANT: Thank you for picking us.