You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello,. How may I be of your assistance today?

USER: I want to meet my Grand dad at San Francisco, can you help me with booking?

ASSISTANT: Sure, Can you provide me your travelling dates?

USER: My travel dates are from 05/18 to 05/20.

ASSISTANT: Please forward your airport codes?

USER: I want fly from OAK to SFO.

ASSISTANT: Let me know your name?

USER: I need a direct flight.

ASSISTANT: Sure.

USER: I am Brian Wilson.

ASSISTANT: wait for a while. There is no flight found with your specified request.

USER: Ok.

ASSISTANT: Thank you for choosing us to serve you.

USER: Thank you for your help.