generate response: 4 people leaving Cambridge and going to London Liverpool Street on Friday, departing after 11:00. Please give me the travel and arrival time as well as the price.. Intent: book_train. Slots: train-bookpeople=4, train-day=friday, train-departure=cambridge, train-destination=london liverpool street, train-leaveat=11:00
Response: Your tickets have been booked. Your reference number is 7LBIW6SB .