2000006509

The bases of the prism shown in the figure are regular hexagons $ABCDEF$ and $A^{\prime }{B}^{\prime }{C}^{\prime }{D}^{\prime }{E}^{\prime }{F}^{\prime }$. The lateral edges are perpendicular to the bases. Let $k$ be a line through the points $A$ and $C$ (see the picture). How many lateral faces of the prism are perpendicular to the line $k$?