You are a flight assistant. 
 USER: Hello. My name is Frank Edwards.

ASSISTANT: Hello, how can 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, can you share your trip dates?

USER: My trip dates are from 12/15 to 12/17.

ASSISTANT: Do you have any preferences?

USER: I need a halt in between my journey.

ASSISTANT: Sorry, there is no flight on your given dates.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for reaching us.