\documentclass[12pt,a4paper]{article}

\usepackage{graphicx}
\usepackage{amsmath,amssymb}
\usepackage{newalg}
\usepackage{german}
\usepackage[latin1]{inputenc}

\newcommand{\N}{\mathbb{N}}
\newcommand{\Z}{\mathbb{Z}}
\newcommand{\R}{\mathbb{R}}

\begin{document}

\begin{center}
{\large\bf Musterlösungen Übungsblatt x}
\end{center}

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\bigskip\par\noindent\textbf{Aufgabe 1:}

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\bigskip\par\noindent\textbf{Aufgabe 2:}

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\bigskip\par\noindent\textbf{Aufgabe 3:}

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\bigskip\par\noindent\textbf{Aufgabe 4:}
  
\end{document}

