[O] How to export an Org file to LaTeX's book class, but without parts?

[Marcin Borkowski]

Hi all,

this is an actual question, but it can be viewed as a continuation of
the "why use LaTeX directly and not Org" thread (disclaimer: from the
POV of an experienced LaTeX user and much less experienced Org-exporter
user).

So, I tried to do the opposite, just to learn something/unlock the "Org
Exporter" skill;-).  I want to export my Org file to the book class
(actually, a class similar to it, but never mind), but I want my
first-level headings to be chapters, not parts.  OTOH, I don't want to
modify org-latex-classes.  Is that possible, and if yes, how to achieve
that?

TIA,

-- 
Marcin Borkowski
http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski
Faculty of Mathematics and Computer Science
Adam Mickiewicz University