  We compute and present the distribution in mass of single and binary neutron
stars, strange stars, and black holes. The calculations were performed using a
stellar population synthesis code. We follow evolution of massive single stars
as well as binaries with high mass primaries. The final product of the latter
evolution can be either a binary composed of a white dwarf and a compact object
(neutron star, black hole, strange star), two compact objects in a binary, or
two single stars if the system was disrupted. We find in binaries a population
of black holes which are more massive than single black holes which are a
product of either binary or single evolution. We also find that if quark stars
exist at all, their population can be as large as the population of black
holes.
