You are a flight assistant. 
 USER: Hi, my name is Lisa Nelson from Phoenix.

ASSISTANT: Hello. How can I assist you?

USER: I need to book a direct flight to attend for my last exam at San Francisco, so please assist me in booking a plane to CA - SFO.

ASSISTANT: Could you provide me your source point?

USER: My source airport code is AZ - PHX.

ASSISTANT:  When are you planning to travel?

USER: I am planning to travel on 04/19 to 04/21.

ASSISTANT: Do you have any preference?

USER: Yes, I can pay up to 500.

ASSISTANT:  We found a connecting flight Frontier with flight number 1002 and fare is 100.

USER: Do not proceed as I need a direct flight.

ASSISTANT: Ok.

USER: Thank you for your assistance.

ASSISTANT:  Thank you for availing us.