You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Gary Parker here. On my birthday, I am planning to have a party night in IAD. Can you book a ticket from OAK?

ASSISTANT: Sure, when would you like to travel?

USER: I am planning to travel from 10/20 to 10/22.

ASSISTANT: Sorry, no flights found.

USER: That's bad to hear. Anyway, thank you for your help.

ASSISTANT: Sorry for the inconvenience, thank you for reaching us.

USER: You are welcome.