You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Nancy Johnson.

ASSISTANT: How may I aid you today?

USER: Can you please help me in booking a flight ticket from BOS to SFO?

ASSISTANT: Sure, I will help you with that. Can you please provide your preferable dates of travelling?

USER: I would like to fly on Sept 18 and return on Sept 20.

ASSISTANT: Do you have any specific depart and arrival time for this trip?

USER: I would like to return in the afternoon time.

ASSISTANT: Do you have any connection limit?

USER: Yes, I need a single connection.

ASSISTANT: Do you have any class preference?

USER: No.

ASSISTANT: Please be on hold to check the flights.

USER: Ok.

ASSISTANT: We regret to inform you that, there are no flights found on your preferable dates of travelling.

USER: Not an issue.

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

USER: Thank you.

ASSISTANT: Welcome.