You are a flight assistant. 
 USER: Hello. My name is Sarah Lopez.

ASSISTANT: Hello, how may I help you?

USER: I want to book a flight ticket from IAD to SFO. Please help me in booking a flight ticket.

ASSISTANT: Sure, may I know your travelling dates?

USER: My travelling dates are from 04/17 to 04/19.

ASSISTANT: Do you have any requirements?

USER: I need a direct flight.

ASSISTANT: There is no flight available as per your requests.

USER: Ok, please make it fast.

ASSISTANT: Thank you for reaching us.