1\documentclass{book}
2\begin{document}
3\part{First Part}
4\chapter{First Chapter}
5\section{First Section}
6\subsection{First Subsection}
7\subsubsection{First Subsubsection}
8\paragraph{First Paragraph}
9\subparagraph{First SubParagraph}
10\chapter{Second Chapter}
11\section{First Section}
12\section{Second Section}
13\subsection{First Subsection}
14\subsection{Second Subsection}
15\subsection{Third Subsection}
16
17\end{document}
18