\documentclass[a4paper, 14pt]{article}
\usepackage{fontspec}
\usepackage[utf8]{inputenc} % UTF-8
\usepackage[T1]{fontenc}
\usepackage{lmodern} % Prévient un bug d'affichage evince lié à [T1]{fontenc}
\usepackage[french]{babel} % francisation
\usepackage[fleqn]{amsmath} % aligne le mode maths à gauche
\usepackage[table, usenames, svgnames]{xcolor} % Couleurs
\usepackage{multicol} % Multi-colonnes
\usepackage{fancyhdr} % Mise en page, en-tête et pied de page
\usepackage{calc} % Opérations
\usepackage[autolanguage]{numprint} % écrituredes virgules
\usepackage{enumitem}
\usepackage{xcolor}


\usepackage[a4paper, dvips, left=1.5cm, right=1.5cm, top=2cm,%
bottom=2cm, marginpar=5mm, marginparsep=5pt]{geometry}
\usepackage[bookmarks=true, bookmarksnumbered=true, pagebackref=true,%
            colorlinks=true,linkcolor=blue,plainpages=true, unicode]{hyperref}
\hypersetup{pdfauthor={Lilian Couchet},pdfsubject={Exercices de
    mathématiques},pdftitle={Exercices}}
%\usepackage{textcomp}
\def\pshlabel#1{\psframebox*[fillcolor=White,framearc=.2]{\footnotesize $#1$}}
\def\psvlabel#1{\psframebox*[fillcolor=White,framearc=.2]{\footnotesize $#1$}}
\setlength{\columnsep}{0pt}
\setlength{\headheight}{18pt}
\newcounter{exo}

\makeatletter
\newcommand\styleexo[1][]{
  \renewcommand{\theenumi}{\arabic{enumi}}
  \renewcommand{\labelenumi}{\textbf{\theenumi.}}
  \renewcommand{\theenumii}{\alph{enumii}}
  \renewcommand{\labelenumii}{\textbf{\theenumii}}
  {\textbf{\underline{\\#1 \theexo}}}
  \par\@afterheading\vspace{0.5\baselineskip minus 0.2\baselineskip}}



\newcommand\exercice[3]{
  \refstepcounter{exo}%
  \noindent
  \begin{minipage}{\textwidth}
    \styleexo[#1]

    #2
    
    #3
  \end{minipage}
  \vspace{1cm}
}

\setlength\parindent{0em}
\setlength\mathindent{0em}

\count1=\year \count2=\year \ifnum\month<8\advance\count1by-1\else\advance\count2by1\fi
\pagestyle{fancy}
\cfoot{\textsl{\footnotesize{Année \number\count1/\number\count2}}}
\rfoot{\textsl{\tiny{Generateur}}}
\lhead{\textsl{\footnotesize{Page \thepage/ \pageref{LastPage}}}}
\chead{\Large{\textsc{ {{title}} }}}


\begin{document}
\currentpdfbookmark{Les énoncés des exercices}{Énoncés}

\setmainfont[
 BoldFont={Liberation Serif Bold}, 
 ItalicFont={Liberation Serif Italic},
 BoldItalicFont={Liberation Serif Bold Italic}
 ]{Liberation Serif}
\def\HS{\hspace{\fontdimen3\font}}
\newcounter{nocalcul}[exo]
\renewcommand{\thenocalcul}{\Alph{nocalcul}}
\raggedcolumns
\setlength{\columnseprule}{0.5pt}

{% for exo in exos %}
  \exercice{Exercice}{ {{ exo.consigne }} }{
    \begin{multicols}{ {{exo.columns}} }\noindent
      \begin{enumerate}
      {% for e in exo.exos%}
        \item ${{e.calcul}}$
      {% endfor %}
      \end{enumerate}
    \end{multicols}
  }
  
{% endfor %}
\label{LastPage}


\newpage

\currentpdfbookmark{Le corrigé des exercices}{Corrigé}
\lhead{\textsl{\footnotesize Page \thepage/ \pageref{LastCorPage}}}
\setcounter{page}{1}
\setcounter{exo}{0}


{% for exo in exos %}
\exercice{Corrigé}{ {{ exo.consigne }} }{
  {% if exo.correction%}
  \begin{multicols}{ {{exo.columns}} }\noindent
    \begin{enumerate}
    {% for e in exo.exos%}
      \item ${{e.correction}}$
    {% endfor %}
    \end{enumerate}
  \end{multicols}

  {% else%}
   Pas de corretion donnée
  {% endif %}

}

{% endfor %}
\label{LastCorPage}



\end{document}