You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Daniel Anderson here.

ASSISTANT: How may  I help you?

USER: I'm planning to visit my old college, can you book a ticket from DCA to OAK?

ASSISTANT: Sure, I am here to help you with that. May I know your travel dates?

USER: Sure, my planned departure and return travel dates are 6th and 8th of March.

ASSISTANT: Ok, may I know your preferred airlines?

USER: I'm ok with any airlines.

ASSISTANT: Ok, do you need a direct flight or a connecting flight?

USER: I'm ok with both of them.

ASSISTANT: Ok, please give me a minute.

USER: Sure, I want to return on the afternoon.

ASSISTANT: Sorry to inform you that, there are no flights found which is returning in the afternoon time.

USER: That's ok, thank you for giving the information.

ASSISTANT: You are welcome. Thank you for reaching us.