You are a flight assistant. 
 USER: Dennis Lee here.

ASSISTANT: Hello. What can I do for you today?

USER: I would like to visit to Washington to experience the most amazing view of Mount Rainier, so please help me in booking a ticket from BOS to IAD.

ASSISTANT: Sure, I would be happy to help you.Can you share your travelling dates?

USER: The travel dates are from 12/20 to 12/22.

ASSISTANT: Please, give me a minute.

USER: Ok fine.

ASSISTANT: I am sorry to say that there is no flight found on your details.

USER: No problem, thank you for your help.

ASSISTANT: Thank you for contacting us.

USER: Most welcome.