\documentclass[12pt,twoside,a4paper]{article} 
\begin{document} 
\begin{tabular}{c|c|c} 
A & B & C \\ 
\hline 
1 & 2 & 3 \\ 
\hline 
4 & 5 & 6 \\
\end{tabular} 
\end{document} 