i need to take a train from cambridge to peterborough .
user
there are hundreds of options , i can narrow it down if you have a day , arrival time or departure time .
assistant
i want to leave on sunday and arrive at 16:00
user
i have plenty of options for you . would you like to leave first thing in the morning or in the afternoon ?
assistant
earlier is better , since i need to be there by 16:00 .