You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: Could you please provide me a service regarding the flight ticket booking from Washington to reach Oakland?

ASSISTANT: Sure, I am glad to help you with your concern.

USER: Thank you.

ASSISTANT: Can you please let me know your trip dates?

USER: I am looking to travel on the dates of April 12th and April 14th.

ASSISTANT: May I know your region airport codes?

USER: The nearest airports to my desired locations are IAD and OAK.

ASSISTANT: Do you have any connection limit preference?

USER: I prefer a single connecting flight.

ASSISTANT: Do you have any class preference?

USER: No but I need a flight which is returning in the evening time.

ASSISTANT: Sure, I will check with that. To proceed further, may I know your name?

USER: My name is Sharon Mitchell.

ASSISTANT: Thank you for sharing all the necessary information, Sharon Mitchell. Regret to inform that there is no evening flight available for the mentioned dates.

USER: It's ok, not a problem with that. Thank you for searching the flight availability.

ASSISTANT: Your patience is appreciated, Sharon Mitchell. Thank you for reaching us.

USER: You are welcome.