You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, may I know how best I can help you today?

USER: My name is Melissa Gonzalez. I would like to book a ticket from DCA to ORD for seeing my children.

ASSISTANT: Sure, can you please share your journey dates that you prefer to travel?

USER: My itinerary travel dates are 09/21 and 09/23.

ASSISTANT: May I know your departure time and arrival time?

USER: My flight departure is in the evening.

ASSISTANT: Do you have any other requirements?

USER: I would prefer business class with single connection.

ASSISTANT:  No flights are available on respective dates of travel.

USER: No problem, Thank you for the information.

ASSISTANT: Thank you.