You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. May I know your good name please?

USER: I am Andrew Young.

ASSISTANT: How may I aid you today?

USER: I want to start from San Francisco on 05/10 to attend robotic workshop and I intend to return on 05/12, can you help me to book a flight ticket?

ASSISTANT: Sure, how much can you afford for the flight ticket?

USER: I need the flight ticket with in the fare limit 200.

ASSISTANT: Please share your airport codes.

USER: I need to start from San Francisco, CA-SFO to reach Dallas, TX-DFW.

ASSISTANT: Ok, give me a minute.

USER: Ok.

ASSISTANT: Thank you for your time. There are no flights found available according to your specifications.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for reaching us.