Minecraft CC - etOS APP - Staircase Mine

--Epuuc
local args = {...}

print("What Y do you want me to mine to?")
local ygoal = tonumber(read())

print("What's my current Y?")
local ypos = tonumber(read())
local diff = ypos-ygoal
while true do
    if diff > 0 then
        turtle.dig()
        turtle.forward()
        turtle.digUp()
        ypos = ypos - 1
        turtle.digDown()
        turtle.down()
        if not turtle.detectDown() and args[1] ~= "false" then
            turtle.placeDown()
        end
    else
        if diff == 0 then break end
        turtle.dig()
        turtle.forward()
        turtle.digUp()
        ypos = ypos + 1
        if not turtle.detectDown() then
            turtle.placeDown()
        end
        turtle.up()
        turtle.digUp()
    end
    if ypos == ygoal then break end
end
print("Y reached")
--Epuuc