b-mine

    function fuel()
    if turtle.getFuelLevel() < 10 then
		for n=1,16 do
			if turtle.getItemCount(n) > 0 then
				turtle.select(n)
				if turtle.refuel(1) then
					turtle.select(1)
				end
			end
		end
      turtle.select(1)
    else
    print("Fuel: "..turtle.getFuelLevel().." ")
        end
    end

    function turn()
      turtle.turnRight()
      turtle.turnRight()
    end

    function tunnel()
      turtle.dig()
	  sleep(0.5)
	  turtle.forward()
	  distance = distance + 1
      turtle.digUp()
      turtle.select(1)
      turtle.placeDown()
      turtle.turnRight()
      turtle.detect()
      turtle.place()
      turn()
      turtle.detect()
      turtle.place()
      turtle.turnRight()

    if distance == 9 then
      turtle.select(16)
      print("Placing Torch...")
      turn()
      turtle.place()
      turn()
      distance = 0
    end
    end

    function back()
    turtle.up()
    turn()
     for j = 1,length do
      turtle.forward()
    --  if turtle.forward() == false then
        turtle.dig()
        turtle.attack()
    --  end
     end
    turtle.down()
    turn()
    end

    write("Tunnel length: ")
    length = read()
    print("Starting...")
    fuel()
	distance = 0
	i = 1
	while i < length do
		tunnel()
	end
	back()
    print("Done...")