  We propose a model with a compensating scalar field whose back reaction to
the cosmological curvature cancels possible vacuum energy density down to the
terms of the order of the time dependent critical energy density. Thus the
model simultaneously solves the mystery of the compensation of vacuum energy
with the accuracy of 120 orders of magnitude and explains existence of the
observed dark energy. At an early stage the suggested cosmological model might
experience exponential expansion without an additional inflaton field.
