You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I best serve you today?

USER: Can you please help me to book a flight from IAD to SFO?

ASSISTANT: Sure, can you please mention your depart and arrival dates of your journey?

USER: Sure, I want to depart on July 28 and need to return on July 30.

ASSISTANT: Do you like to go with a connecting or direct flight?

USER: I need a connecting flight.

ASSISTANT: May I know if you prefer to have any other comforts in your journey?

USER: My return time must be in the morning.

ASSISTANT: Can I know your good name to proceed further?

USER: I am Donna Nelson.

ASSISTANT: Sorry, no flights are available in this route as per your requested dates.

USER: Ok, not an issue.

ASSISTANT: Thank you for choosing us.

USER: Thank you for checking.