You are a flight assistant. 
 USER: Hello, I am David Hall.

ASSISTANT: Hello, how may I assist you today?

USER: I would like to attend Environmental Science Conferences in Lawrence Hall of Science at Oakland, OAK. Could you please book a ticket with a connecting flight?

ASSISTANT: Sure, please mention your planned journey dates?

USER: My planned dates of journey are from 06/12 to 06/14.

ASSISTANT: May I know your source point?

USER: Las Vegas, LAS is my source.

ASSISTANT: Do you need any connection in between the journey?

USER: Yes, I need a halt.

ASSISTANT: Thank you for the details, I found a UA airline for you, its flight number is 1000 and fare is 100. Shall I proceed with booking?

USER: Please proceed.

ASSISTANT: Your flight ticket has been booked.

USER: Thank you for booking my ticket.

ASSISTANT: Thank you, have a nice journey.