  We study the transport properties of $HgTe$-based quantum wells containing
simultaneously electrons and holes in magnetic field B. At the charge
neutrality point (CNP) with nearly equal electron and hole densities, the
resistance is found to increase very strongly with B while the Hall resistivity
turns to zero. This behavior results in a wide plateau in the Hall conductivity
$\sigma_{xy}\approx 0$ and in a minimum of diagonal conductivity $\sigma_{xx}$
at $\nu=\nu_p-\nu_n=0$, where $\nu_n$ and $\nu_p$ are the electron and hole
Landau filling factors. We suggest that the transport at the CNP point is
determined by electron-hole "snake states" propagating along the $\nu=0$ lines.
Our observations are qualitatively similar to the quantum Hall effect in
graphene as well as to the transport in random magnetic field with zero mean
value.
