I have my template here
\begin{document}
\begin{table}[!h]
\begin{center}
\makebox[\textwidth][c] %[l]
{
\begin{tabular}{c|c|c}
\hline
Topic 1 & Topic 2 & Topic 2 \\
\hline
33333 & 44444 & 55555\\
\hline
aaaaa & bbbbb & 55555\\
\hline
\end{tabular}
}
\hspace*{0mm}
\end{center}
\caption{}
\label{table:example-app}
\end{table}
\end{document}
How do I make:
a. the "Topic 2" in the 1st row (2nd and 3rd columns) combined to be a single block, and has the vertical line in between removed?
b. As well as combine "55555" occur in the 2nd and 3rd row (of 3rd column) to be a single block, and has the horizontal line in between removed?
c. In the desired new Table, I hope that "Topic 2" and "55555" only occur once in the new form. Namely, repeated items are combined.
I tried to use the multirow but I failed (cannot compile in TexShop). Maybe there is a neat way to do that.

