Consider a triangle $ABC$ with $AB=AC$, and $D$ as the foot of the altitude from the vertex $A$. The point $E$ lies on the side $AB$ such that $\angle ACE = \angle ECB = 18^{\circ}$. If $AD = 3$, find the length of the segment $CE$.

Let's think step by step and output the final answer within \boxed{}.
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