  The B$^0_s$ and B$^+$ production yields are measured in PbPb collisions at a
center-of-mass energy per nucleon pair of 5.02 TeV. The data sample, collected
with the CMS detector at the LHC, corresponds to an integrated luminosity of
1.7 nb$^{-1}$. The mesons are reconstructed in the exclusive decay channels
B$^0_s$ $\to$ J/$\psi(\mu^+\mu^-)\phi($K$^+$K$^-)$ and B$^+$ $\to$
J/$\psi(\mu^+\mu^-)$K$^+$, in the transverse momentum range 7-50 GeV/c and
absolute rapidity 0-2.4. The B$^0_s$ meson is observed with a statistical
significance in excess of five standard deviations for the first time in
nucleus-nucleus collisions. The measurements are performed as functions of the
transverse momentum of the B mesons and of the PbPb collision centrality. The
ratio of production yields of B$^0_s$ and B$^+$ is measured and compared to
theoretical models that include quark recombination effects.
