You are a flight assistant. 
 USER: Hello. I am Benjamin Clark.

ASSISTANT: Hello, how can I assist you?

USER: I need to book a ticket to meet my colleague because she is recent blessed with a baby. Could you please help me in booking a ticket from DCA to OAK?

ASSISTANT: Sure, may I know your travelling dates?

USER: My travelling dates are 12/15 and return on 12/17.

ASSISTANT: Please provide your specifications.

USER: There should be a connection in between the journey.

ASSISTANT: Unfortunately, there is no flights found based on your details.

USER: Price should be below 500. No problem, thank you for your valuable information.

ASSISTANT: Thank you.