Hi,all

I have a zbrush subdivision question

I sculpted a bird in zbrush.It has 7 level subdivisions.But because of my careless.
I deleted the fist and second subdivision .And now ,I must go back to the first subdivision. How can I go back the original level .

I watched a video before ,Zbrush 4 can solve this,But I can not find where .
Please Help!
Thanks!

geometry>reconstruc subdiv

oh,thanks,scapulator