local up = 0
local right_movement = 0
local last = "left"

while true do
    if turtle.detectUp() == true then

        while (turtle.detectUp()) do
            local success, t = turtle.inspectUp()
            if  (string.find(t.name, "dirt") == nil) then
                turtle.digUp()
                turtle.up()
                up = up + 1
            else
                break
            end
        end
        repeat
            turtle.down()
            up = up - 1
        until up == 0
    else
        repeat
            turtle.down()
            up = up - 1
        until up == 0
    end
end