  The pseudoscalar sum rules of the heavy-light quark systems are used for
extracting simultaneously the c,b quark masses and the decay constants
f_D_(s),f_B_(s) of the D_(s),B_(s) mesons. To order alpha_s^2, one obtains the
running quark masses: m_c(m_c)=(1.10 \pm 0.04) GeV, m_b(m_b)=(4.05\pm 0.06)
GeV, the perturbative pole masses: M_c=(1.46\pm 0.04) GeV, M_b=(4.69\pm 0.06)
GeV, and the decay constants: f_D=(205\pm 20) MeV, f_B=(203\pm 23) MeV and
f_D_s=(235\pm 24) MeV, f_B_s=(236\pm 30) MeV, in the normalization where f_\pi=
130.56 MeV. The fitted values of the pole and running masses satisfy quite well
their three-loop perturbative relation. The value f_D = f_B confirms earlier
findings from the sum rule that the 1/M_P^1/2 heavy quark symmetry scaling law
is affected by large 1/M_P corrections.
