IR-TST 2021 Problem 1

In acute scalene triangle $ABC$ the external angle bisector of $\angle BAC$ meet $BC$ at point $X$ .Lines $l_b$ and $l_c$ which tangents of $B$ and $C$ with respect to $(ABC)$ .The line pass through $X$ intersects $l_b$ and $l_c$ at points $Y$ and $Z$ respectively. Suppose $(AYB)\cap(AZC)=N$ and $l_b\cap l_c=D$ . Show that $ND$ is angle bisector of $\angle YNZ$ . Proposed by Alireza Haghi