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\begin{tikzpicture} \def \h{4} \def \s{1} \draw (0,0) rectangle (\h,\h); \node (a) at (1,1) {$id$}; \draw (\h+\s,0) rectangle (2*\h+\s,\h); \node (a) at (1,1) {$1-id$}; \draw (0,\h+\s) rectangle (\h,2*\h+\s); \node (a) at (1,1) {$0$}; \draw (\h+\s,\h+\s) rectangle (2*\h+\s,2*\h+\s); \node (a) at (1,1) {$1$}; \end{tikzpicture}