You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello!tell me how may I assist you?

USER: I am Patrick Campbell. I would like to travel from IL-ORD to MA-BOS. Will you please help to get a flight ticket?

ASSISTANT: OK,can you please tell me your travelling dates?

USER: My preferable dates are 05/11 and 05/13.

ASSISTANT: Can you please tell me your preferable connection limit & price of your ticket?

USER: My preferable price limit is 500 with single connection only.

ASSISTANT: Sorry, to say there are no flights available on your requirements. Thank you.

USER: OK, no problem. Thank you for your service.