i need to book a train from cambridge and norwich on wednesday and i need to be there at 15:30 .
user
when would you like to leave by ?
assistant
i do not care when i leave as long as i get there by 15:30 .
user
there are 9 trains matching your query . shall i book 1 ?
assistant
can i get the departure and travel time of the train arriving closest to 15:30 ?
user
the travel time is 79 minutes .
assistant
and the departure time please ? for the train that arrives closest to 15:30 ?