I'm doing slides with beamer using the mtheme. This theme includes the slide number in the bottom of the page using this code:
\begin{beamercolorbox}[wd=\textwidth,ht=3ex,dp=3ex,leftskip=0.3cm,rightskip=0.3cm]{structure}%
\hfill\usebeamerfont{page number in head/foot}%
\insertframenumber%
\end{beamercolorbox}%
}
I wanted to the number to appear as x/X, being X the total number of slides, which can be displayed via \inserttotalframenumber. So i change the third line above to:
\insertframenumber/\inserttotalframenumber%
Now, the problem is that I have a slide at the end that should NOT count in the total number of frames, and so the result is that it's showing x/X, begin X one unit bigger than it should.
How could I do it so it displays \inserttotaframenumber-1. I saw calc allows for simple calculations but using the package and writing just \insertotalframenumber-1 does not work.
Can I do this some how?
Thank you.