You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Karen Hall.

ASSISTANT: How can I help you?

USER: I am looking for a flight from DCA to HOU, can you help me?

ASSISTANT: Please provide your travel dates.

USER: My travelling dates are 18 and 20 of June.

ASSISTANT: Do you have any preferences?

USER: I would like to return in the evening with a connecting flight.

ASSISTANT: Sorry, I did not find any flights for you.

USER: It's ok, not a problem, thank you.

ASSISTANT: Thank you for reaching us.