Racing Dead

*When there's no more room in hell, the dead will race the earth.* Spooky and $N$ other ghosts are racing against each other. The racetrack is a straight line. To make things interesting, the ghosts start at different positions. The $i$-th ghost starts $A_i$ meters away from the finish line, and will drive at a constant speed of $B_i$ units. Unfortunately, the timer used by the ghosts can onl