Charged-particle pseudorapidity density in Pb$-$Pb  and p$-$Pb for the $5\%$ most central collisions, and for pp collisions with INEL$>0$ trigger class. For symmetric collision systems (Pb$-$Pb and pp) the data has been symmetrised around ${\eta=0}$ and points for ${\eta>3.5}$ have been reflected around ${\eta=0}$. The boxes around the points and to the right reflect the uncorrelated and correlated, with respect to pseudorapidity, systematic uncertainty, respectively The relative correlated, normalisation, uncertainties are evaluated at ${\rm d}N_{\rm ch}/{\rm d}\eta|_{\eta=0}$. The lines show fits of Eq. 1 (Pb$-$Pb and pp) and Eq. 2 (p$-$Pb) to the data (discussed in Section 4). Please note that the ordinate has been cut twice to accommodate for the very different ranges of the charged-particle pseudorapidity densities.