[K12OSN] Script help

[mrok12osn at eastgranby.k12.ct.us]

I need to walk a directory tree and issue a

chmod u=rwx,g=rwxs,o-rwx

on all (sub)directories, but not files, in the tree.  Can anyone help?  I
am pretty script illiterate.

Mark Orenstein
East Granby, CT School System