= Solution
\b[No.] In a <red-black tree> with no red nodes, equal <black height> forces every <graph path> from the root to an absent-child position to have the same length. A real node cannot have exactly one real child: the two paths through that node would then have different numbers of black nodes. Recursively, every real level must be full. The tree is therefore a <perfect binary tree>.
With $h$ real levels its size is $1+2+\cdots+2^{h-1}=2^h-1$. A size of $23$ would require $2^h=24$, which is impossible for an <integer> $h$. The black null sentinels are not counted among the $23$ stored entries. This is the <all-black red-black tree size criterion>.
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