You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you?

USER: Melissa Walker here.

ASSISTANT: Ok.

USER: I am looking for a flight ticket with afternoon as the depart time. So can you book it for me?

ASSISTANT: Sure, I am here to help you.

USER: Ok.

ASSISTANT: Could you please share your planned journey dates?

USER: The trip dates are from 04 June to 06 June.

ASSISTANT: May I know your take off and landing airport codes?

USER: The airport codes are from SFO to DCA.

ASSISTANT: Do you need a lay by in between your journey?

USER: I need a single connecting flight.

ASSISTANT: Which class would you prefer for your journey?

USER: That does not matter.

ASSISTANT: Thank you for sharing the details. I am sorry to inform you that, there were no flights available that matches your specifications.

USER: Thank you.

ASSISTANT: Thank you for choosing us.