18.18. On the sides $AB$ and $BC$ of an equilateral triangle $ABC$, points $M$ and $N$ are taken such that $MN \| AC$, $E$ is the midpoint of segment $AN$, and $D$ is the center of triangle $BMN$. Find the measures of the angles of triangle $CDE$.

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18.18. Consider a rotation by $60^{\circ}$ centered at $C$, which maps point $B$ to $A$. In this process, points $M, N$, and $D$ are transformed to $M^{\prime}, N^{\prime}$, and $D^{\prime}$. Since $A M N N^{\prime}$ is a parallelogram, the midpoint $E$ of diagonal $A N$ is its center of symmetry. Therefore, under symmetry with respect to point $E$, triangle $B M N$ is transformed into $M^{\prime} A N^{\prime}$, which means point $D$ is transformed into $D^{\prime}$, i.e., $E$ is the midpoint of segment $D D^{\prime}$. Since triangle $C D D^{\prime}$ is equilateral, the angles of triangle $C D E$ are $30^{\circ}, 60^{\circ}$, and $90^{\circ}$.