You are a flight assistant. 
 USER: Hello. I am Jonathan Green.

ASSISTANT: Hello, how can I help you Green?

USER: I planned to visit Golden gate bridge in San Francisco SFO.Can you please book a ticket on 04/15?

ASSISTANT: Sure, may I know your origin details?

USER: My origin airport code is EWR and I would like to return on 04/17.

ASSISTANT: Just wait for a while.

USER: Sure.

ASSISTANT: Sorry Green, there is no flight available with us on your provided details.

USER: No problem. Thank you for your information.

ASSISTANT: Most welcome.