You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, do you need any help from us?

USER: I would like to attend my friend's wedding anniversary at Houston, please help me in booking a ticket from DCA to HOU.

ASSISTANT: Sure, could you please share your departure and arrival day?

USER: I would like to return on July 23 and return on July 25.

ASSISTANT: Sure, could I have your name please?

USER: My name is Elizabeth Johnson.

ASSISTANT: Ok, do you need direct or connecting flight?

USER: I need a connecting flight.

ASSISTANT: Ok, do you have any other specifications?

USER: I would like to depart in the evening.

ASSISTANT: Sorry, there is no flight with your requested time.

USER: Ok, no issues. Thank you for your information.

ASSISTANT: You are welcome, have a great day.