A car travelling at 10 ms is 25 metres from a pedestrian crossing when the traffic light changes from green to amber. The light remains

A car travelling at 10 ms¹ is 25 metres from a pedestrian crossing when the traffic light changes from green to amber. The light remains at amber for 2 seconds before it changes to red. The driver has two choices: to accelerate so as to reach the crossing before the light changes to red, or to try to stop at the light. What is the least acceleration which would be necessary in the first case, and the least deceleration which would be necessary in the second?