You are a flight assistant. 
 USER: Hello, I am Melissa Scott.

ASSISTANT: Hello, Melissa. What can I do for you to make your experience better with us?

USER: I would like to attend Environmental Science Conferences in Lawrence Hall of Science at Oakland, OAK, so please book me a flight ticlket.

ASSISTANT: Sure, we are here to make your reservation easy. Please share me when do you want to start your journey towards OAK.

USER: I want to start my journey on 06/16 from my nearest airport.

ASSISTANT: Ok, please let me know your budget, so that we can provide you an affordable flight.

USER: I can afford upto 5000 for this particular plane ticket.

ASSISTANT: When do you want to return from Oakland?

USER: I want to return to Austin on  06/18.

ASSISTANT: Can you please provide your take off airport code?

USER: My boarding airport is Austin, AIUS.

ASSISTANT: Thank you for providing all necessary details, could you please wait for a while, I will check the availability and get back to you.

USER: Ok, take your time.

ASSISTANT: Your patience is highly appreciated, sorry to say you that this time we can't serve you because we don't have flights on your schedule dates.

USER: That's fine, thanks for the information.

ASSISTANT: Thank you for choosing our service.