Invariant mass distributions of $\pi^+\pi^-$ (left panel) and p$\pi^-$ (middle panel) pairs in central Pb-Pb collisions at $\sNN$ = 2.76 TeV. The hatched areas show the regions of the $\Kzs$ and $\Lambda$ peaks and of the combinatorial background. The right-hand panel shows the reconstruction efficiencies (including the candidate selection cuts) as a function of transverse momentum for central (0-5$\%$) and peripheral (80-90$\%$) collisions.