You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hi,how may I assist you?

USER: This is William Miller. Could you please help me to book a flight ticket?

ASSISTANT: OK,please help me by providing your airport codes?

USER: I want to travel from MN-MSP to TX-DFW.

ASSISTANT: May I know your travelling dates please?

USER: My onward journey is on 12/21 and return would be on 12/23. And I need 1 connection flight with a price limit of 5000.

ASSISTANT: I am really sorry that there is no flight available for you.

USER: OK, thank you for your information.

ASSISTANT: Have a nice day.