You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello. How may I aid you?

USER: Could you please book a ticket from Houston, TX-HOU to Philadelphia, PA-PHL.

ASSISTANT: Sure, I am here to help you. When would you like to travel?

USER: Departure date is 06/22 and return is by 06/24.

ASSISTANT: For booking the ticket. May I know your name?

USER: My name is Anna Green.

ASSISTANT: As per your data, I found a flight with Frontier airlines and the ticket fare is 100. Shall I proceed for booking?

USER: Please book direct flight.

ASSISTANT: Anna sorry for inconvenience, no flights are available with your requirements.

USER: Thanks.

ASSISTANT: Thank you Anna for approaching us.