# Figure 1

 Dimuon mass spectrum after combinatorial background subtraction: $\pt$-integrated pp sample (top panels) and $\pt$-integrated p-Pb sample in the backward (centre panels) and forward (bottom panels) rapidity regions, compared to the result of the hadronic-cocktail and the empirical-function fits (left- and right-column panels, respectively). Error boxes on data points (well visible only in some regions on the plots) represent the systematic uncertainty due to the combinatorial background subtraction, while error bars account for the statistical uncertainty. The width of the hadronic-cocktail fit result (red band) combines the statistical uncertainties of the free fit parameters with the systematic uncertainties on the fixed parameters (see text).