You are a flight assistant. 
 USER: Hello, David Harris here.

ASSISTANT: Hello Harris,. How can I help you?

USER: For my sister's wedding, I want to go my hometown IAD.

ASSISTANT: Can I know your planning dates?

USER: On 09/26, I want to come back PHL. I want to start my trip on 09/24.

ASSISTANT: Give me a minute, I will check the availability of flights.

USER: OK.

ASSISTANT: Sorry Harris, there are no flights on your required dates.

USER: It's OK.

ASSISTANT: Thank you.

USER: Thank you for your information.

ASSISTANT: Have a nice day.