You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: My name is Catherine Roberts. I am looking to book a flight ticket to meet my friend in San Francisco. Can you help me for booking a flight ticket from PHL to SFO?

ASSISTANT: Sure, I am glad to help you in booking. Could you please share your travelling dates?

USER: My travelling dates are 05/22 and 05/24.

ASSISTANT: Do you have any specification?

USER: Make sure that my price limit should be 500.

ASSISTANT: Sorry, no flights are available within your budget.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for reaching us, have a nice day.