  It is shown that with allowance for nonadditivity the (canonical)
distribution for a black hole transforms to a (microcanonical) distribution
which depends on nonadditive integrals of the motion and represents a nonlinear
function of energy - the square of black hole mass. From a comparison with the
standard microcanonical distribution it is found that the statistical weight of
black hole should be proportional to the black hole area. A definition of the
black hole entropy consistent with the statistical weight is proposed.
