You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you for the day?

USER: My name is Michelle Thompson. I would like to reserve a flight ticket from New York to San Francisco, can you please help me to search the flight?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: When you are willing to travel?

USER: I am willing to travel on the dates of Apr 28 and Apr 30.

ASSISTANT: Please wait for a moment. Can you help me with your airport codes?

USER: The preferred airport codes are LGA and SFO.

ASSISTANT: Do you have any class preference?

USER: No, I am ok with any class.

ASSISTANT: Sorry, we found no flights on your given dates.

USER: It's ok, not a problem with that one. Anyways thank you for your valuable time.

ASSISTANT: Thank you for reaching us.

USER: You are welcome.