You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Amy Nelson here.

ASSISTANT: Amy Nelson, how can I assist you?

USER: I would like to visit Oakland to spend my holidays, please help me in booking a ticket from DCA to OAK.

ASSISTANT: Sure, please provide your itinerary dates.

USER: My planned travel dates are on Jan 29 and Jan 31.

ASSISTANT: Do you have any specifications?

USER: I need a direct flight.

ASSISTANT: At what time do you want to travel?

USER: I would like to return in the evening.

ASSISTANT: Please wait for a while.

USER: Sure, take your time.

ASSISTANT: Sorry, no flights are available in the evening.

USER: Ok, no issues. Thank you for your information.

ASSISTANT: Thank you for choosing us.