$\begin{array}{*{20}{c}}
{R =  - CH - Cl}\\
{|\,\,}\\
{\,\,\,\,C{H_3}}
\end{array}\,\,\,\,,\,\,\,\,\,\,\,\,\,\,\begin{array}{*{20}{c}}
{S =  - CH - Cl}\\
{|\,\,}\\
{Br}
\end{array}$