diff --git a/example_long.tex b/example_long.tex
deleted file mode 100644
index 48456f7..0000000
--- a/example_long.tex
+++ /dev/null
@@ -1,107 +0,0 @@
-\documentclass[aspectratio=169]{beamer}
-
-\input{template_long.tex}
-
-%% use one of the two below
-% \colorlet{main}{red!50!black}
-% \colorlet{main}{purple}
-
-%-------------------main body-------------------------%
-
-\author{Your Name}
-\title{Presentation Title}
-\date{January 1, 2018}
-
-\begin{document}
-
-\frame[plain]{\titlepage}
-
-\begin{frame}
-\frametitle{Outline}
-\tableofcontents
-\end{frame}
-
-\section{Page Title}
-
-\frame{\frametitle{Outline}\tableofcontents[currentsection]}
-
-\begin{frame}
-\frametitle{Page Title}
-
-TeX - LaTeX Stack Exchange is a question and answer site for users of TeX, LaTeX, ConTeXt, and related typesetting systems.
-
-\vspace{0.4cm}
-
-unordered list below
-
-\begin{itemize}
-\item The first item
-\item The second item
-\item The third item
-\item The fourth item
-\end{itemize}
-
-\end{frame}
-
-\section{Display Theorem}
-
-\frame{\frametitle{Outline}\tableofcontents[currentsection]}
-
-\subsection{first subsection}
-
-\subsection{second subsection}
-
-\begin{frame}
-  \frametitle{Display Theorem}
-  \begin{theorem}
-    $1 + 2 = 3$
-  \end{theorem}
-  \begin{proof}
-    $$1 + 1 = 2$$
-    $$1 + 1 + 1 = 3$$
-  \end{proof}
-\end{frame}
-
-\section{Sample frame title}
-
-\frame{\frametitle{Outline}\tableofcontents[currentsection]}
-
-\begin{frame}
-\frametitle{Sample frame title}
-This is a text in second frame.
-For the sake of showing an example.
-
-\begin{itemize}
- \item Text visible on slide 1
- \item Text visible on slide 2
- \item Text visible on slide 3
-\end{itemize}
-
-\vspace{0.3cm}
-
-another example
-
-\begin{itemize}\itemsep0em
- \item Text visible on slide 1
- \item Text visible on slide 2
- \item Text visible on slide 3
-\end{itemize}
-\end{frame}
-
-\begin{frame}
-  \begin{proof}
-    $$
- \frac{1}{\displaystyle 1+
-   \frac{1}{\displaystyle 2+
-   \frac{1}{\displaystyle 3+x}}} +
- \frac{1}{1+\frac{1}{2+\frac{1}{3+x}}}
-$$
-$$\int_0^\infty e^{-x^2} dx=\frac{\sqrt{\pi}}{2}$$
-\begin{equation} x=y+3 \label{eq:xdef}
-\end{equation}
-In equation (\ref{eq:xdef}) we saw $\dots$
-  \end{proof}
-\end{frame}
-
-
-\end{document} 
\ No newline at end of file
diff --git a/example_short.tex b/example_short.tex
deleted file mode 100644
index 2896674..0000000
--- a/example_short.tex
+++ /dev/null
@@ -1,103 +0,0 @@
-\documentclass{beamer}
-
-\input{template_short.tex}
-
-%% use one of the two below
-% \colorlet{main}{red!50!black}
-% \colorlet{main}{purple}
-
-%-------------------main body-------------------------%
-
-\author{Your Name}
-\title{Presentation Title}
-\date{January 1, 2018}
-
-\begin{document}
-
-\frame[plain]{\titlepage}
-
-\begin{frame}
-\frametitle{Outline}
-\tableofcontents
-\end{frame}
-
-\section{Page Title}
-
-\begin{frame}
-\frametitle{Page Title}
-
-TeX - LaTeX Stack Exchange is a question and answer site for users of TeX, LaTeX, ConTeXt, and related typesetting systems.
-
-\vspace{0.4cm}
-
-unordered list below
-
-\begin{itemize}
-\item The first item
-\item The second item
-\item The third item
-\item The fourth item
-\end{itemize}
-
-\end{frame}
-
-\section{Display Theorem}
-
-\subsection{first subsection}
-
-\subsection{second subsection}
-
-
-
-\begin{frame}
-  \frametitle{Display Theorem}
-  \begin{theorem}
-    $1 + 2 = 3$
-  \end{theorem}
-  \begin{proof}
-    $$1 + 1 = 2$$
-    $$1 + 1 + 1 = 3$$
-  \end{proof}
-\end{frame}
-
-\section{Sample frame title}
-
-\begin{frame}
-\frametitle{Sample frame title}
-This is a text in second frame.
-For the sake of showing an example.
-
-\begin{itemize}
- \item Text visible on slide 1
- \item Text visible on slide 2
- \item Text visible on slide 3
-\end{itemize}
-
-\vspace{0.3cm}
-
-another example
-
-\begin{itemize}\itemsep0em
- \item Text visible on slide 1
- \item Text visible on slide 2
- \item Text visible on slide 3
-\end{itemize}
-\end{frame}
-
-\begin{frame}
-  \begin{proof}
-    $$
- \frac{1}{\displaystyle 1+
-   \frac{1}{\displaystyle 2+
-   \frac{1}{\displaystyle 3+x}}} +
- \frac{1}{1+\frac{1}{2+\frac{1}{3+x}}}
-$$
-$$\int_0^\infty e^{-x^2} dx=\frac{\sqrt{\pi}}{2}$$
-\begin{equation} x=y+3 \label{eq:xdef}
-\end{equation}
-In equation (\ref{eq:xdef}) we saw $\dots$
-  \end{proof}
-\end{frame}
-
-
-\end{document} 
\ No newline at end of file
diff --git a/examples/long_green.pdf b/examples/long_green.pdf
deleted file mode 100644
index d5dd884..0000000
Binary files a/examples/long_green.pdf and /dev/null differ
diff --git a/examples/long_red.pdf b/examples/long_red.pdf
deleted file mode 100644
index f634dc0..0000000
Binary files a/examples/long_red.pdf and /dev/null differ
diff --git a/examples/short_green.pdf b/examples/short_green.pdf
deleted file mode 100644
index 99819d0..0000000
Binary files a/examples/short_green.pdf and /dev/null differ
diff --git a/examples/short_red.pdf b/examples/short_red.pdf
deleted file mode 100644
index 764953c..0000000
Binary files a/examples/short_red.pdf and /dev/null differ
diff --git a/imgs/long_green.jpg b/imgs/long_green.jpg
deleted file mode 100644
index 0ea18e7..0000000
Binary files a/imgs/long_green.jpg and /dev/null differ
diff --git a/imgs/long_red.jpg b/imgs/long_red.jpg
deleted file mode 100644
index c7d26b3..0000000
Binary files a/imgs/long_red.jpg and /dev/null differ
diff --git a/imgs/short_green.jpg b/imgs/short_green.jpg
deleted file mode 100644
index cf27ff3..0000000
Binary files a/imgs/short_green.jpg and /dev/null differ
diff --git a/imgs/short_red.jpg b/imgs/short_red.jpg
deleted file mode 100644
index c8186cb..0000000
Binary files a/imgs/short_red.jpg and /dev/null differ
diff --git a/template_long.tex b/template_long.tex
deleted file mode 100644
index fe7c788..0000000
--- a/template_long.tex
+++ /dev/null
@@ -1,66 +0,0 @@
-% This file contains some settings , it need to be input by your tex file.
-
-\usepackage[english]{babel}
-% add sidebar on the right
-\useoutertheme[width=3\baselineskip,right]{sidebar}
-% TOC(table of content) using ordered list 
-\setbeamertemplate{section in toc}[sections numbered]
-% unordered list using solid point
-\setbeamertemplate{itemize item}{$\bullet$}
-% set frame title for each page
-\setbeamertemplate{frametitle}
-  {\vspace{-0.5cm}
-   \insertframetitle
-   \vspace{-0.5cm}}
-% delete original navigation
-\setbeamertemplate{navigation symbols}{}
-% set footline
-\makeatother
-\setbeamertemplate{footline}
-{
-  \leavevmode%
-  \hbox{%
-  \begin{beamercolorbox}[wd=.4\paperwidth,ht=2.25ex,dp=1ex,center]{author in head/foot}%
-    \usebeamerfont{author in head/foot}\insertshortauthor
-  \end{beamercolorbox}
-
-  \begin{beamercolorbox}[wd=.6\paperwidth,ht=2.25ex,dp=1ex,center]{title in head/foot}%
-    \usebeamerfont{title in head/foot}\insertshorttitle\hspace*{13em}
-    \insertframenumber{} / \inserttotalframenumber\hspace*{0ex}
-  \end{beamercolorbox}}
-
-  \vskip0pt%
-}
-\makeatletter
-
-
-% define color
-%\definecolor{alizarin}{rgb}{0.82, 0.1, 0.26} % a kind of red
-%\definecolor{DarkFern}{HTML}{407428} % a kind of green
-%\colorlet{main}{DarkFern!100!white} % first setting way(with color newly defined)
-%\colorlet{main}{red!70!black} % second setting way(with internal color by setting gradient)
-\definecolor{bistre}{rgb}{0.24, 0.17, 0.12} % a kind of black
-\definecolor{mygrey}{rgb}{0.52, 0.52, 0.51} % a kind of grey
-\colorlet{text}{bistre!100!white} % from now on, `text` implies the color defined
-\colorlet{main}{green!50!black}
-
-% set colors to elements, fg is the color itself, bg is the background color, !num! implies gradient
-\setbeamercolor{title}{fg=main}
-\setbeamercolor{frametitle}{fg=main}
-\setbeamercolor{section in toc}{fg=text}
-\setbeamercolor{normal text}{fg=text}
-\setbeamercolor{block title}{fg=main,bg=mygrey!14!white}
-\setbeamercolor{block body}{fg=black,bg=mygrey!10!white}
-\setbeamercolor{qed symbol}{fg=main} % frame after proof
-\setbeamercolor{math text}{fg=black}
-% footline color
-\setbeamercolor{author in head/foot}{fg=black, bg=mygrey!5!white}
-\setbeamercolor{title in head/foot}{fg=black, bg=mygrey!5!white}
-\setbeamercolor{structure}{fg=main, bg=mygrey!10!white} % set sidebar color
-
-% margin left and right, and fontsize of sidebar
-\def\swidth{2.3cm}
-\setbeamersize{sidebar width right=\swidth}
-\setbeamersize{sidebar width left=\swidth}
-\setbeamerfont{title in sidebar}{size=\scriptsize}
-\setbeamerfont{section in sidebar}{size=\tiny}
diff --git a/template_short.tex b/template_short.tex
deleted file mode 100644
index 253730d..0000000
--- a/template_short.tex
+++ /dev/null
@@ -1,43 +0,0 @@
-% This file contains some settings , it need to be input by your tex file.
-
-\usepackage[english]{babel}
-% TOC(table of content) using ordered list
-\setbeamertemplate{section in toc}[sections numbered]
-% unordered list using solid point
-\setbeamertemplate{itemize item}{$\bullet$}
-% set frame title for each page
-\setbeamertemplate{frametitle}
-  {\vspace{1cm}
-   \insertframetitle
-   \vspace{-0.5cm}}
-% delete original navigation
-\setbeamertemplate{navigation symbols}{}
-% set footline
-\setbeamertemplate{footline}[text line]{%
-    \hfill\strut{%
-        \scriptsize\sf\color{black!60}%
-        \quad\insertframenumber
-    }%
-    \hfill
-}
-
-
-% define color
-%\definecolor{alizarin}{rgb}{0.82, 0.1, 0.26} % a kind of red
-%\definecolor{DarkFern}{HTML}{407428} % a kind of green
-%\colorlet{main}{DarkFern!100!white} % first setting way(with color newly defined)
-%\colorlet{main}{red!70!black} % second setting way(with internal color by setting gradient)
-\definecolor{bistre}{rgb}{0.24, 0.17, 0.12} % a kind of black
-\definecolor{mygrey}{rgb}{0.52, 0.52, 0.51} % a kind of grey
-\colorlet{text}{bistre!100!white} % from now on, `text` implies the color defined
-\colorlet{main}{green!50!black}
-
-% set colors to elements, fg is the color itself, bg is the background color, !num! implies gradient
-\setbeamercolor{title}{fg=main}
-\setbeamercolor{frametitle}{fg=main}
-\setbeamercolor{section in toc}{fg=text}
-\setbeamercolor{normal text}{fg=text}
-\setbeamercolor{block title}{fg=main,bg=mygrey!14!white}
-\setbeamercolor{block body}{fg=black,bg=mygrey!10!white}
-\setbeamercolor{qed symbol}{fg=main} % frame after proof
-\setbeamercolor{math text}{fg=black}