You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you today?

USER: Can you help me to book a flight ticket from SFO to EWR?

ASSISTANT: Sure, I am happy to help you with that. Can I know your travelling dates?

USER: Yes, Please book a ticket for the dates July 21 and 23 respectively.

ASSISTANT: May I know your name?

USER: Ok, please book a flight ticket on the name James Williams.

ASSISTANT: Do you have any other requirements?

USER: Ok, please book a ticket for a economy class flight and I need a connecting fight.

ASSISTANT: Ok, wait for a minute.

USER: SUre.

ASSISTANT: Sorry to say that, there are no flight's available based on your travelling dates.

USER: That is ok, thank you for assisting me.

ASSISTANT: Thank you for approaching us.