local layers = 30
local depth = 0
local lastDepth = 0

function digRow()
  turtle.digDown()
	turtle.forward()
	turtle.digDown()
	turtle.forward()
	turtle.digDown()
end

function digLayer()
  digRow()
	turtle.turnRight()
	turtle.forward()
	turtle.turnRight()
	digRow()
	turtle.turnLeft()
	turtle.forward()
	turtle.turnLeft()
	digRow()
	turtle.turnLeft()
	turtle.forward()
	turtle.forward()
	turtle.turnLeft()
	turtle.forward()
	turtle.forward()
	turtle.turnLeft()
	turtle.turnLeft()
	layers = layers + 1
	depth = depth + 1
end

function returnItems()
  lastDepth = depth
	while depth > 0 do
	  turtle.up()
		depth = depth - 1
	end
	turtle.drop()
	while depth < lastDepth do
	  turtle.down()
		depth = depth + 1
	end
end

while layers > 0 do
  if depth > lastDepth + 5 then
	  returnItems()
	end
  digLayer()
	turtle.down()
end