# Move chapter to top and change its format

I would like to change position of my chapter title more to the top of the page and also change format of it to: "0 Introduction" "1 Something" "1.1 Something" "2 Something" etc. instead of "Chapter 1 - Something"

and also, how do I change the distance between chapter title and beginning of the text?

Thank you very much for any advice.

Use the memoir class (a superset of book and report) with the section chapter style.

% chapstyleprob.tex  SE 567585
\documentclass{memoir}
\usepackage{lipsum}

\chapterstyle{section} %% this seems to be the style you want
\setlength{\beforechapskip}{-1cm} %% raise title, adjust to suit
\begin{document}
\setcounter{chapter}{-1}  %% first chapter number will be 0
\chapter{Introduction}
\thispagestyle{empty}
\lipsum[1]
\section{First section}
\lipsum[2]
\end{document}