You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Patrick Young.

ASSISTANT: How can I help you?

USER: I am planning to travel from DCA to CLT. Can you please help me to book a ticket?

ASSISTANT: Let me know your travelling dates.

USER: I want to start on July 28 and return on July 30.

ASSISTANT: Do you have any preference?

USER: I want to return in the evening. I need a connecting flight.

ASSISTANT: Sorry, no flights found for your travelling dates.

USER: Ok, not an issue. Thank you.

ASSISTANT: Thank you.