You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: I am Donald Clark, I am willing to book a flight ticket to Washington for an event there which is held by me. So, can you please help me to book a flight ticket from Seattle, WA - SEA?

ASSISTANT: Sure, I will help you. Can you please tell me your preferable dates?

USER: My preferable dates are 09/15 and 09/17.

ASSISTANT: Ok, what's your destination airport code?

USER: My destination code is DC - DCA.

ASSISTANT: Sorry, there are no flights from SEA to DCA on the dates you have provided.

USER: It's ok I will go with another resources to reach there. Any way thank you for the information.

ASSISTANT: You are welcome.