function checkFuel()
                turtle.select(15)
end

 function moveUp()
        checkFuel()
        while(turtle.up()==false)do turtle.digUp() end
end

function moveDown()
        checkFuel()
        while(turtle.down()==false)do turtle.digDown() end
end

function move()
        checkFuel()
        while(turtle.forward()==false)do turtle.dig() end
end

function moveBack()
        checkFuel()
        while(turtle.back()==false)do end
end

local args = { ... }

function main()
	local quarryWidth

	if(#args == 1) then
		quarryWidth = tonumber(args[1])
		if(quarryWidth<2 or quarryWidth>64) then
			print("Invalid Width")
			return
		end
	else
		print("Usage: "..shell.getRunningProgram().." <diameter>")
		return
	end

	for temp2=2,1,-1 do
		for temp=quarryWidth-1,1,-1 do
			move()
		end
		turtle.select(2)
		turtle.digDown()
		turtle.placeDown()
		moveBack()
		turtle.select(1)
		turtle.place()

		for temp=quarryWidth-1,2,-1 do
			moveBack()
		end
		turtle.turnRight()
	end

end

main()