  A general theory is developed to describe graphene with arbitrary number of
isolated impurities. The theory provides a basis for an efficient numerical
analysis of the charge transport and is applied to calculate the minimal
conductivity of graphene with resonant scatterers. In the case of smooth
resonant impurities conductivity grows logarithmically with increasing impurity
concentration, in agreement with renormalization group analysis for the
symmetry class DIII. For vacancies (or strong on-site potential impurities) the
conductivity saturates at a constant value that depends on the vacancy
distribution among two sublattices as expected for the symmetry class BDI.
