The ladder rule

• Everytime a ladder encountered, go down it, and to the right as far as possible (still going down any ladder encountered)
• If can't go further right, remember the current 'floor', climb back up to the top and keep on going right
• If something fails, backtrack - i.e. go back to last ladder encountered; go down it to the next floor, after the one last visited, and then back up to the right