\documentclass[12pt]{book}

\input{../../header}

\lstset{inputpath=../code}
\graphicspath{{images/}}

\typein[\pagenumber]{Number of first page}
\typein[\chapternumber]{Chapter number}
\setcounter{page}{\pagenumber}
\setcounter{chapter}{\chapternumber}

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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{document} 

\input{spectral}

\section{TODO}
\begin{itemize}
\item hm, let's see, maybe we could start writing it...
  
\item
\end{itemize}

\end{document}