Extracted source size $r_\text{core}$ of primordial p$-\pi^+$ pairs as a function of the pair transverse mass. The results are compared with the $r_\text{core}$ extracted from p$-$p pairs  as well as $\pi^\pm-\pi^\pm$ and $\text{p--}\text{K}^+$ pairs in HM pp collisions at $\sqrt{s}=13$TeV by ALICE. The lines (boxes) show the statistical (systematic) uncertainties. The gray band represents the extrapolated scaling of p$-$p pairs.