while true do
    turtle.select(1)
    while turtle.detect() == false do
        if turtle.compareDown() == true then
            turtle.forward()
        elseif turtle.compareDown() == false then
            turtle.back()
            turtle.turnLeft()
        end
    end
    turtle.select(2)
    if turtle.compare() == true then
        turtle.dig()
        turtle.forward()
        turtle.digUp()
        turtle.up()
        turtle.digUp()
        turtle.up()
        turtle.digUp()
        turtle.up()
        turtle.down()
        turtle.down()
        turtle.down()
    else if turtle.compare() == false then
        turtle.turnLeft()
        turtle.forward()
        turtle.turnLeft()
    end
    turtle.select(3)
    if turtle.compare() == true then
        turtle.dig()
        turtle.forward()
    else if turtle.compare() == false then
        turtle.turnLeft()
        turtle.forward()
        turtle.turnLeft()
    end
end