grow

while true do
  turtle.select(1)
  for i = 1,13 do
    turtle.suckDown()
  end
  for i = 1, 13 do
    turtle.select(i)
    if turtle.compareTo(14) then
      turtle.dropUp()
    else
      if turtle.compareTo(15) then
        turtle.dropUp()
      else
        if turtle.compareTo(16) then
          turtle.dropUp()
        else
          turtle.dropDown()
        end
      end
    end
  end
  sleep(10)
end