Professional way to prepare programming contest problems

This is a brief manual for formatting statements of your problems.
If you are planning to write statements only to show them in PDF format, you can use all available commands which are supported by LaTeX. However, if you are planning to show statements in HTML, you need to know that there is a limited set of TeX commands which are supported by our systems. All supported commands when rendering to HTML are provided below:
$ $
$$ $$
' '
<< >>
`` ''
~
"
\bf
\textbf
\it
\textit
\t
\tt
\texttt
\emph
\underline
\sout
\textsc
\tiny
\scriptsize
\small
\normalsize
\large
\Large
\LARGE
\huge
\Huge
\begin{itemize}
\begin{enumerate}
\begin{lstlisting}
\begin{center}
\begin{tabular}
\hline
\cline
\multicolumn
\multirow
\url
\href
\includegraphics
\epigraph
When MathJax is used for rendering formulas (which is true for all problems created after 1 Jun 2021), the commands used in inline mode are not restricted by our systems. It means you can use any mathematical symbol supported by modern LaTeX.
Formulas using MathJax:
These are inline formulas: $x$, $a_i^2 + b_i^2 \le a_{i+1}^2$. Afterwards... 
These are inline formulas: $$$x$$$, $$$a_i^2 + b_i^2 \le a_{i+1}^2$$$. Afterwards... 
These are centered formulas: $$x,$$ $$a_i^2 + b_i^2 \le a_{i+1}^2.$$ Afterwards... 
These are centered formulas: $$$$$$x,$$$$$$ $$$$$$a_i^2 + b_i^2 \le a_{i+1}^2.$$$$$$ Afterwards... 
Some complex formula: $$P(S  E[S] \ge t) \le 2 \exp \left( \frac{2 t^2 n^2}{\sum_{i = 1}^n (b_i  a_i)^2} \right).$$ 
Some complex formula: $$$$$$P(S  E[S] \ge t) \le 2 \exp \left( \frac{2 t^2 n^2}{\sum_{i = 1}^n (b_i  a_i)^2} \right).$$$$$$ 
If you want to start new paragraph, insert newline not once but twice:
First paragraph. Still first paragraph. 
First paragraph. Still first paragraph. 
First paragraph. Second paragraph. 
First paragraph. Second paragraph. 
Text style commands:
\bf{This text is bold.}or \textbf{This text is bold.} 
This text is bold. 
\it{This text is italic.}or \textit{This text is italic.} 
This text is italic. 
\t{This text is monospaced.}or \tt{This text is monospaced.}or \texttt{This text is monospaced.} 
This text is monospaced. 
\emph{This text is underlined.}or \underline{This text is underlined.} 
This text is underlined. 
\sout{This text is struck out.} 
This text is struck out. 
\textsc{This text is capitalized.} 
This text is capitalized. 
Text size commands:
\tiny{This text is 70\% of normal size.} 
This text is 70% of normal size. 
\scriptsize{This text is 75\% of normal size.} 
This text is 75% of normal size. 
\small{This text is 85\% of normal size.} 
This text is 85% of normal size. 
\normalsize{This text is 100\% of normal size.}or just This text is 100\% of normal size. 
This text is 100% of normal size. 
\large{This text is 115\% of normal size.} 
This text is 115% of normal size. 
\Large{This text is 130\% of normal size.} 
This text is 130% of normal size. 
\LARGE{This text is 145\% of normal size.} 
This text is 145% of normal size. 
\huge{This text is 175\% of normal size.} 
This text is 175% of normal size. 
\Huge{This text is 200\% of normal size.} 
This text is 200% of normal size. 
List commands:
This is the unordered list: \begin{itemize} \item This is the first item; \item This is the second item. \end{itemize} 
This is the unordered list:

This is the ordered list: \begin{enumerate} \item This is the first item; \item This is the second item. \end{enumerate} 
This is the ordered list:

Source code inserting commands:
Some C++ source code (autodetecting and highlighting): \begin{lstlisting} #include <iostream> int main() { int a, b; std::cin >> a >> b; std::cout << a + b << std::endl; } \end{lstlisting} 
Some C++ source code (autodetecting and highlighting):

Hyperlink insertion commands:
Link to website: \url{https://codeforces.com/}. 
Link to website: https://codeforces.com/. 
Link to website with caption: \href{https://codeforces.com/}{Codeforces}. 
Link to website with caption: Codeforces. 
If you want to center content, use the following command:
\begin{center} This content is centered. $abacaba$ \end{center} 
This content is centered. $$$abacaba$$$ 
If you want to insert some images in your statement, first you need to upload your image via Statement Resource Files section at the bottom of Statements page. When you successfully uploaded your image, you can use them in statements. Let's assume the image named 'polygonlogo.png' is already uploaded:
Unscaled image: \includegraphics{polygonlogo.png} 
Unscaled image: 
It is strongly recommended to center and caption your images:
\begin{center} \includegraphics{polygonlogo.png} \small{Centered unscaled image.} \end{center} 

\begin{center} \includegraphics[scale=1.5]{polygonlogo.png} \small{Centered scaled image.} \end{center} 

If you want to insert tables in you statements, you can use syntax from TeX including specification of text alignment for each column and borders:
Simple table without borders: \begin{tabular}{ll} First & Second \\ Third & Fourth \end{tabular} 
Simple table without borders:


More complex table with borders: \begin{tabular}{lcr} \hline Left aligned column & Centered column & Right aligned column \\ \hline Text & Text & Text \\ \hline \end{tabular} 
More complex table with borders:


Scoring table example: \begin{center} \begin{tabular}{  c  c  c  c  } \hline \bf{Group} & \bf{Add. constraints} & \bf{Points} & \bf{Req. groups} \\ \hline $1$ & $b = a + 1$ & $30$ &  \\ \hline $2$ & $n \le 1\,000$ & $10$ & examples \\ \hline $3$ & $n \le 10^7$ & $20$ & $2$ \\ \hline $4$ &  & $40$ & $1$, $3$ \\ \hline \end{tabular} \end{center} 
Scoring table example:


\begin{center} \begin{tabular}{cc} \includegraphics{polygonlogo.png} & \includegraphics{polygonlogo.png} \end{tabular} \small{Images side by side example.} \end{center} 

If you need to create more complex tables, you can use the following commands:
Advanced scoring table example (colspan and rowspan): \begin{center} \begin{tabular}{ccccc} \hline \multirow{2}{*}{\bf{Group}} & \multicolumn{2}{c}{\bf{Add. contraints}} & \multirow{2}{*}{\bf{Points}} & \multirow{2}{*}{\bf{Req. groups}} \\ \cline{23} & $n$ & $a_i$ & & \\ \hline $1$ & $n \le 10$ &  & $12$ &  \\ \hline $2$ & $n \le 500$ & $a_i \le 100$ & $19$ &  \\ \hline $3$ &  & $\sum a_i \le 10^9$ & $41$ &  \\ \hline $4$ &  &  & $28$ & $1$, $2$, $3$ \\ \hline \end{tabular} \end{center} 
Advanced scoring table example (colspan and rowspan):


Simultaneous colspan and rowspan: \begin{center} \begin{tabular}{ccc} \hline \multicolumn{2}{c}{\multirow{2}{*}{Cell}} & Cell \\ \cline{33} \multicolumn{2}{c}{} & Cell \\ \hline Cell & Cell & Cell \\ \hline \end{tabular} \end{center} 
Simultaneous colspan and rowspan:

Miscellaneous:
If you want to quote single character, use single quotes: `a'. In Russian statements use <<these double quotes>>. As for the long dashes~ use these like that. In English statements use ``these double quotes''. As for the long dashes " use these like that. 
If you want to quote single character, use single quotes: 'a'. In Russian statements use «these double quotes». As for the long dashes — use these like that. In English statements use "these double quotes". As for the long dashes — use these like that. 
\epigraph{\it{Some inspirational citation...}}{ Author of citation, \it{Source}} Legend starts here... 
Some inspirational citation...
— Author of citation, Source
Legend starts here... 