Pentagon Inscribed in a Circle

Pentagon $ABCDE$ is inscribed in circle $O$ such that $AE$ is the diameter of circle $O$ and $CD = DE$. Let $K$ be a point on the circle such that points $D$, $O$, and $K$ are collinear. If $\angle ABC = 140^\circ$, what is the measure (in degrees) of $\angle KBE$?