You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you for today?

USER: I am Donna Martin, planning to visit Oakland. Can you please book me a ticket from DCA to OAK?

ASSISTANT: I am glad to help you with that. Can you please provide your planned dates of your journey?

USER: My preferable journey dates are from 03/20 to 03/22.

ASSISTANT: Please wait for sometime.

USER: Sure, I will wait for your reply.

ASSISTANT: Sorry to say this Donna, there are no flights which travels to your region.

USER: Ok, not an issue. I will find any alternate for this trip. Thank you for providing information.

ASSISTANT: You are welcome, thank you for reaching out here. Hope you have a nice day ahead.