\tikzstyle{hidden_neuron}=[circle,draw=red!50,fill=orange!10,thick,minimum size=.2mm]
\tikzstyle{input_neuron}=[circle,draw=blue!50,fill=blue!10,thick,minimum size=1mm]
\tikzstyle{output_neuron}=[circle,draw=green!50,fill=green!20,thick,minimum size=1mm]
\tikzstyle{input}=[circle,draw=black!50,fill=black!20,thick,minimum size=.2mm]

\begin{tikzpicture}

	%	 layer 1
%	\node [neuron_type] (var_name) at (X,Y)  {$Text$} ;
	\node [input_neuron] (ain1) at (5.5,4)  {$D$} ;
	\node [input_neuron] (ain2) at (7,4)  {$I$} ;
	
	%	layer2
%	\node [input_neuron] (in3) at (4,3)  {$C$} ;
	\node [input_neuron] (ain4) at (6.25,2.75)  {$G$};
	\node [input_neuron] (ain5) at (7.75,2.75)  {$S$} ;
	
	%	layer3
	\node [input_neuron] (ain6) at (6.25,1.5)  {$L$} ;
	\node (input1) at (6.25,0.5) {\textbf{(a)}};

	\node [input_neuron] (bin1) at (8.5,4)  {$D$} ;
	\node [input_neuron] (bin2) at (10,4)  {$I$} ;
	
	%	layer2
	%	\node [input_neuron] (in3) at (4,3)  {$C$} ;
	\node [input_neuron] (bin4) at (9.25,2.75)  {$G$};
	\node [input_neuron] (bin5) at (10.75,2.75)  {$S$} ;
	
	%	layer3
	\node [input_neuron] (bin6) at (9.25,1.5)  {$L$} ;
	\node (input1) at (9.25,0.5) {\textbf{(b)}};
	
	\draw [->, line width=0.5mm] (ain1) -- (ain4);
	\draw [->, line width=0.5mm] (ain2) -- (ain4);
	\draw [->, line width=0.5mm] (ain2) -- (ain5);
%	\draw [->] (in5) -- (in6);
%	\draw [->] (in3) -- (in6);
	\draw [->, line width=0.5mm] (ain4) -- (ain6);
	
	
	\draw [->, line width=0.5mm] (bin1) -- (bin4);
	\draw [->, line width=0.5mm] (bin2) -- (bin4);
	\draw [->, line width=0.5mm] (bin2) -- (bin5);
	\draw [->] (bin5) -- (bin6);
%	\draw [->] (in3) -- (in6);
	\draw [->, line width=0.5mm] (bin4) -- (bin6);
	
\end{tikzpicture}