\makeatletter
\@ifundefined{stylecentrale}
{\def\resetlevel{section}}
{%
\renewcommand\thesection{\Roman{section}}%
\renewcommand\thesubsection{\thesection.\Alph{subsection}}%
\def\resetlevel{subsection}
}


\theoremstyle{plain}
\theoremheaderfont{\bfseries}
\theorembodyfont{\upshape}
\theoremseparator{. }
\theoremsymbol{}
\newtheorem*{important}{Important}
\newtheorem*{rappel}{Rappel}

\usepackage{xfrac}
\usepackage{xparse}
\usepackage{comment}

\newif\ifcorrige
\def\corr{\filigrane{\Huge CORRIG\'E --- CORRIG\'E}\global\corrigetrue}
\newif\ifcorrigeseul
\def\corrseul{\filigrane{\Huge CORRIG\'E --- CORRIG\'E}\global\corrigeseultrue}

\usepackage{xstring}
\IfEndWith{\jobname}{\detokenize{-ENONCE}}{\let\corr\relax\let\corrseul\relax}{}
\IfEndWith{\jobname}{\detokenize{-PROF}}{\corr\let\corr\relax\let\corrseul\relax}{}
\IfEndWith{\jobname}{\detokenize{-CORRIGE}}{\corrseul\let\corr\relax\let\corrseul\relax}{}

\def\pasenonce{
  \excludecomment{question}
  \excludecomment{enonce}
  \excludecomment{qcmrep}
  \excludecomment{qcm}
  }

\def\avecenonce{\newenvironment{enonce}{}{}
  \newtheorem{question}{Question}[\resetlevel]
  \def\skipcorrige{}
  \newtheorem{qcm}{QCM}
  %
  \NewDocumentEnvironment{qcmrep}{o}
  {\IfValueT{##1}{\begingroup\setlength\columnseprule{0pt}\begin{multicols}{##1}}\begin{enumerate}\renewcommand\theenumi{\Alph{enumi}}}{\end{enumerate}\IfValueT{##1}{\end{multicols}\endgroup}}}





\AtBeginDocument{%
\ifcorrige
  \immediate\typeout{Mode professeur}
  \makeatletter\IfStrEq{\@subtitle}{}{}{\subtitle{Corrigé}}\makeatother
  \newenvironment{corrige}{\begin{mdframed}[backgroundcolor=gray!20, skipbelow=1ex]}{\end{mdframed}}
  \newenvironment{comcorrige}{\begin{mdframed}[backgroundcolor=gray!20, skipbelow=1ex]}{\end{mdframed}}
  \newenvironment{qcmcorr}{\begin{mdframed}[backgroundcolor=gray!20, skipbelow=1ex]}{\end{mdframed}}
  \avecenonce
\else\ifcorrigeseul
  \immediate\typeout{Mode corrige}
  \makeatletter\IfStrEq{\@subtitle}{}{}{\subtitle{Corrigé}}\makeatother
  \pasenonce
  \newtheorem{corrige}{Question}[\resetlevel]
  \newtheorem{qcmcorr}{QCM}
  \newenvironment{comcorrige}{}{}
  \def\skipcorrige{\stepcounter{corrige}}
\else
  \immediate\typeout{Mode enonce}
  \excludecomment{corrige}
  \excludecomment{comcorrige}
  \excludecomment{qcmcorr}
  \avecenonce  
\fi\fi
}

\DeclareInstance{xfrac}{cinqdemi}{text}{scale-factor=1, h-scale=1.25, slash-left-kern=-2.5pt, slash-right-kern=-2.25pt}

\def\cinqdemi{\sfrac[cinqdemi]{5}{2}}

\endinput