\begin{table}
   \centering
   \begin{tabular}{|l|*{12}{c|}}
   \hline
   Roman&A&B&G&D&E&Z&Y&H&I&K&L&M\\
   \hline
   Greek&A & B & $\Gamma$ & $\Delta$ & E & Z & H & $\Theta$ & I & K &
   $\Lambda$ & M \\
   \hline\hline
   Roman&N&C&O&P&R&S&T&U&F&X&Q&W\\
   \hline
   Greek&N & $\Xi$ & O & $\Pi$ & P & $\Sigma$ &
   T & $\Upsilon$ & $\Phi$ & X & $\Psi$ & $\Omega$ \\
   \hline\hline
   Roman&a&b&g&d&e&z&y&h&i&k&l&m\\
   \hline
   Greek&   $\alpha$ & $\beta$ & $\gamma$ & $\delta$ & $\epsilon$ & $\zeta$ &
   $\eta$ & $\theta$ & $\iota$ & $\kappa$ &
   $\lambda$ & $\mu$ \\
   \hline\hline
   Roman&n&c&o&p&r&s&t&u&f&x&q&w\\
   \hline
   Greek& $\nu$ & $\xi$ & o & $\pi$ & $\rho$ & $\sigma$ &
   $\tau$ & $\upsilon$ & $\phi$ & $\chi$ & $\psi$ & $\omega$ \\
   \hline
   \end{tabular}
\caption{Roman characters corresponding to Greek characters}
\label{greek}
\end{table}
