You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: Can you help me to book a flight ticket from OAK to LAX?

ASSISTANT: Sure, I will help you. May I know your planned journey dates please?

USER: Ok, please for the dates Sept 3rd and Sept 5th respectively.

ASSISTANT: Can I have your name please?

USER: Yes, my name is Melissa Perez.

ASSISTANT: Do you have any connection preference?

USER: Ok, please book a connecting flight.

ASSISTANT: May I know your class preference?

USER: Yes, I need a economy class flight.

ASSISTANT: Do you have any other preferences?

USER: Ok, please check for a flight which depart during evening.

ASSISTANT: Melissa Perez, no flights has been found on your specifications.

USER: Ok, that is not a problem. Thank you for assisting me.

ASSISTANT: Thank you for choosing us.