You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: Can you help me to book a flight ticket from IAD to ATL?

ASSISTANT: Please provide your travelling dates.

USER: My travel dates are Apr, 10 and Apr, 12.

ASSISTANT: Do you have airline preference?

USER: No.

ASSISTANT: Is there specification?

USER: I need to depart at evening time with connecting flight.

ASSISTANT: May I know your name?

USER: Patricia King here.

ASSISTANT: Sorry, there are no flights with your requirement.

USER: Not a problem, thank you for the information.

ASSISTANT: Thank you. Have a nice day ahead!.