The Hannoi Towers is a game formed by 3 towers and some
rings with different diameters.

The rules are this:


i)   At the beginning of the game, the rings are in a decreasing
     order in only one tower.

     When we move one ring from a tower to another is called a
  movement. 

ii)  A movement can be done only with the smallest ring in the tower and
     to a tower with strictly bigger rings than it.

iii) The game ends whed we've moved all the rings from one tower to
     another according (i) and (ii).