tun

function countblocks()
    return 8
end

function Swap()
    turtle.dig()
    turtle.place()
end

function SwapDown()
    turtle.digDown()
    turtle.placeDown()
end

function SwapUp()
    turtle.digUp()
    turtle.placeUp()
end

function refill_blocks()
    turtle.select(16)
    turtle.place()

    for i=1,14 do
        if turtle.getItemCount(i) == 0 then
            while turtle.getItemSpace(i) ~= 0 do
                turtle.select(i)
                turtle.suck()
            end
        end
    end
    turtle.select(16)
    turtle.dig()
end

function TunnelIter()
    turtle.dig()
    turtle.forward()
    turtle.turnRight()
    Swap()
    SwapDown()
    turtle.turnLeft()
    turtle.turnLeft()
    turtle.forward()
    Swap()
    SwapDown()
    turtle.digUp()
    turtle.up()
    Swap()
    SwapUp()
    turtle.turnRight()
    turtle.turnRight()
    turtle.dig()
    turtle.forward()
    Swap()
    SwapUp()
    turtle.down()
    turtle.turnLeft()
end

function main( args )
    print(args)
    local tunlen = tonumber(args[1])
    local i = 0
    while i < tunlen do
        if turtle.getFuelLevel < 10 then
            if countblocks() >= 8 then
                TunnelIter()
                i=i+1
            else
                refill_blocks()
                turtle.select(1)
            end
        else
            turtle.refuel(15)
        end
    end
end

arg = {...}
main(arg)