\documentclass{vjc-prob}
% You don't have to load packages amsmath and amssymb,
% since these packages are loaded automatically.
% Enter here the year (eg. 30 in the year 2020) of the competition and
% the category for which the problem is intended.
\year{30}
\category{II}
% Enter here the author of the problem and his university.
\author{Name Surname}
\university{University}
\begin{document}
\begin{problem}
Write here text of the problem. You can, of course, use some
$$mathematics\,.$$
\end{problem}
\begin{origin}
If you want to specify origin of the problem, write it here.
\end{origin}
\begin{remark}
If you have some remark to the problem, write it here.
\end{remark}
\begin{solution}
Write here solution of the problem.
If the solution needs some lemmae, use the following environments.
\begin{proclaim}{Lemma}
$E=md^2$.
\end{proclaim}
\begin{proof}
It is obvious.
\end{proof}
Substituting $d=c$ in the Lemma we obtain the desired result.
\end{solution}
\begin{remark}
If you have some remark to the solution, write it here.
\end{remark}
\begin{solution}[Another Solution]
You can write more than solution.
\end{solution}
\end{document}