i need a train going to cambridge that'll leave after 12:15 .
user
what day of the week do you want to travel
assistant
trusday , i need to leave by the london liverpool street station .
user
the tr3257 leaves at 13:39 for 16.60 pounds . would you like me to book that for you ?
assistant
yes . also , what will be the arrival time ? and , what is the train id ? thanks so much !