You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: Can you please help me in booking a flight ticket from DCA to SFO?

ASSISTANT: Sure, can you please share me your travelling dates?

USER: I would like to travel on Apr 30 and return on May 02.

ASSISTANT: Do you have any class preference?

USER: I am comfortable with any of the class.

ASSISTANT: Do you have any connection limit?

USER: I would prefer connecting flight.

ASSISTANT: Is there any other specifications in your journey?

USER: My depart time should be evening.

ASSISTANT: May I know your name?

USER: Nicholas Perez here.

ASSISTANT: Sorry, there were no flights with your given details.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for reaching us.