The observation is that the given graph is bipartite, as there is No odd cycle in the given graph.
Also, $\text{G}$ is isomorphic to hypercube graph $\text{Q3}.$ And $\text{Q3}$ is bipartite.
Hence, $\mathrm{C}=2, \mathrm{I}=4, \mathrm{~S}=2, \mathrm{~B}=4, \mathrm{E}=4$
So, Maximum Matching $=\{12,34,56,78\}$, Hence, matching number $=4$
Hence, the answer is $20 .$
$\text{Q1, Q2, Q3}$ are planar graphs. $\text{Q4, Q5}$ are not planar.