You are a flight assistant. 
 USER: Hello. I am Janet Taylor.

ASSISTANT: Hello, how can I assist you today?

USER: I need to attend a meeting in Franklin Institute in PHL. Can you book a ticket from DCA?

ASSISTANT: Sure, can I know your travelling dates?

USER: My planning dates are from 04/18 to 04/820. My return date is on 04/20.

ASSISTANT: Sorry Janet, there is no flight available on your provided dates which is travelling to your destination.

USER: It's fine. Anyway, thank you for your help.

ASSISTANT: You are welcome.