4. On the side $AB$ of triangle $ABC$, a point $K$ is marked, and on the sides $AC$ and $BC$, points $L$ and $M$ are chosen respectively such that $AK = AL$ and $BK = BM$. It turns out that the lines $LM$ and $AB$ are parallel. The tangent at point $L$ to the circumcircle of triangle $KLM$ intersects the segment $CK$ at point $D$, and a line passing through $D$ and parallel to side $AB$ intersects side $BC$ at point $E$. Find the angle $\angle DEO$, where $O$ is the center of the circumcircle of triangle $KLM$.