**Please comment your solutions, questions and remarks.**.

This funny riddle I heard from Marcin Sabok.

There are *n* ants on the unit interval, [0,1]. Each has a direction, left or right. In the picture above there are three ants and the directions are left, right, left. Each ant is moving with the speed 1 meter/second and the length of the unit interval is 1 meter. If two ants collide, then both of them turn around and continue moving in the new (opposite) direction. If an ant reaches an end of the unit interval, it drops. How long does it take, at most, for all ants to drop? You may assume that the length of an ant is 0.

Level [tex]\frac{3}{2}[/tex] / 5