You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I would like to book a flight ticket to meet my friend in Boston, can you help me for booking a flight ticket from DFW to BOS?

ASSISTANT: Sure, please share your planned travel dates.

USER: My travelling dates are Sep 15 and Sep 17.

ASSISTANT: Do you have any specific depart and return time preference?

USER: My return time is afternoon.

ASSISTANT: Do you have any other preference?

USER: I need a single connecting flight.

ASSISTANT: May I know your name please?

USER: My name is Samuel Young.

ASSISTANT: Sorry to inform you that we don't have any flight available for your journey details.

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

ASSISTANT: Thank you for reaching us.

USER: Welcome.