In this task, you are given a conversation between a flight agent and the customer. You are given 4 options and you need to select the goal of the conversation. It is provided as part of customer's context, which has to be one of the following: `book`: Make a new reservation, `cancel`: Cancel an existing reservation, `no_flight`: No flight found for the customer's preference, `no_reservation`: No reservation / No change / No cancellation was made in the conversation, mostly enquiring details
Example: customer: Hi. 
 agent: Hello. How can I help you? 
 customer: I would like to change my existing reservation as my plan to go for a holiday trip got postponed. Can you please help me with this? 
 agent: Sure, may I know your name please? 
 customer: My name is Anthony Phillips. 
 agent: Please wait a moment. 
 customer: Sure. 
 agent: Unfortunately there is no reservation found with your given name. 
 customer: Not a problem, thank you for checking. 
 agent: Thank you for choosing us.
Example solution: no_reservation
Example explanation: Here the customer has not asked for any booking, he just wanted to update his already booked flight, so the status would be no_reservation

Problem: customer: Hello. 
 agent: Hello. How may I assist you? 
 customer: Can you help me to book a flight ticket from OAK to LAX? 
 agent: Sure, I will help you. May I know your planned journey dates please? 
 customer: Ok, please for the dates Sept 3rd and Sept 5th respectively. 
 agent: Can I have your name please? 
 customer: Yes, my name is Melissa Perez. 
 agent: Do you have any connection preference? 
 customer: Ok, please book a connecting flight. 
 agent: May I know your class preference? 
 customer: Yes, I need a economy class flight. 
 agent: Do you have any other preferences? 
 customer: Ok, please check for a flight which depart during evening. 
 agent: Melissa Perez, no flights has been found on your specifications. 
 customer: Ok, that is not a problem. Thank you for assisting me. 
 agent: Thank you for choosing us.
Solution: no_flight