  In the framework of the effective low-energy model for High-$T_c$ cuprates
with account for three-centers interaction terms and spin fluctuations the
properties of normal and superconducting phases of p- and n-type cuprates are
investigated. Microscopic model parameters were obtained from ARPES data on
undoped compounds. Obtained evolution of the chemical potential with doping,
Fermi Surface at optimal doping, and $T_c(x)$ phase diagram for n-type cuprates
are in remarkably good agreement with the experiment. It is shown that the
spin-exciton mechanism due to singlet-triplet hybridization takes place in
p-type, although it is too small to reproduce observed qualitative difference
between p- and n-type cuprates.
