A fun drive in an amusement park runs between two spots that are 2.0 km apart. For safety reasons the acceleration of the drive is limited to ±4.0 m/s2, and the jerk, or rate of change of acceleration, is limited to ±1.0 m/s2. The drive has a maximum speed of 144 km/h. If the shortest time taken by the drive to travel between the spots is n2, The value of 'n' is ______.