You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you?

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

ASSISTANT: May I know your trip dates?

USER: Sure, my planned travel dates are July 30 and Aug 01.

ASSISTANT: Do you prefer any specifications?

USER: I mostly prefer for a normal-cost airlines.

ASSISTANT: May I know your name?

USER: Myself William Martin.

ASSISTANT: Please wait.

USER: Sure, I will wait for your response.

ASSISTANT: Thank you for waiting, sorry to inform you that unfortunately there is no flights available by the given details.

USER: That's ok, no problem. Thank you for the information.

ASSISTANT: Thank you.