Nether1

    function fuel()
            fuelLevel = turtle.getFuelLevel()
                    if fuelLevel == "unlimited" or fuelLevel > 10 then
                            return
                    end

            function tryRefuel()
                    for n=6,16 do
                            if turtle.getItemCount(n) > 0 then
                                    turtle.select(n)
                                    if turtle.refuel(1) then
                                            print("Fuel: "..turtle.getFuelLevel().."")
                                            turtle.select(3)
                                            return true
                                    end
                            end
                    end
                    turtle.select(3)
                    return false
            end

            if not tryRefuel() then
                    print( "Add more fuel to continue." )
                            while not tryRefuel() do
                                    sleep(1)
                            end
                    print( "Resuming Tunnel." )
            end
    end

    function turn()
            turtle.turnLeft()
            turtle.turnLeft()
    end

    function dig()
            turtle.dig()
            sleep(1)
    end

    function tunnel()
        if turtle.getItemCount(3) <= 5 then
            turtle.select(4)
        elseif turtle.getItemCount(4) <= 5 then
            turtle.select(5)
        else turtle.select(3)
        end
    turtle.dig()
    turtle.forward()
    turtle.placeDown()
    turtle.turnRight()
    turtle.dig()
    turtle.forward()
    turtle.placeDown()
    turtle.dig()
    turtle.forward()
    turtle.placeDown()
    turtle.digUp()
    turtle.up()
    turn()
    turtle.digUp()
    turtle.dig()
    turtle.forward()
    turtle.digUp()
    turtle.dig()
    turtle.forward()
    turtle.digUp()
    turtle.down()
    turtle.turnRight()
    end

    function torch()
        if distance == 20 then
            turtle.select(2)
            turtle.turnRight()
            turtle.place()
            turtle.turnLeft()
        end
        distance = 0
    end

    function chest()
        if turtle.getItemCount(16) > 0 then
            turn()
            turtle.select(1)
            turtle.place()
                for n = 6, 16 do
                    turtle.select(n)
                    turtle.drop()
                    sleep(1)
                end
            turtle.select(1)
            turtle.dig()
            turn()
        end
    end

    function back()
        turn()
        while  j > 1 do
            if turtle.forward() == true then
                fuel()
                j = j - 1
            else
                dig()
            end
        end
        turtle.down()
        turn()
    end

            -- Main-Script --
    print("Slot 1: Enderchest")
    print("Slot 2: Torch")
    print("Slot 3: Cobblestone / Netherrack")
    print("Slot 4: Cobblestone / Netherrack")
    print("Slot 5: Cobblestone / Netherrack")
    print("Fuel: "..turtle.getFuelLevel().."")
    write("Tunnel length: ")
    length = tonumber(read())
    print("Starting...")
    i = 1
    j = 1
    distance = 1
    while i <= length do
        fuel()
        chest()
        tunnel()
        torch()
        i = i + 1
        j = j + 1
        distance = distance +1
    end
    back()
    print("Done...")