The DsTau (NA65) experiment at CERN was proposed to measure an inclusive differential cross-section of $D_s$ production
in $p$-$A$ interactions. As this process is a main source of tau neutrino production, its study is necessary for a measurement of the tau neutrino interaction
cross-section which, in turn, enables a search
for new physics effects such as testing the Lepton Flavour Universality of the Standard Model in the neutrino interactions.
The DsTau detector is based on the nuclear emulsion technique providing an excellent spatial resolution
providing a very high spatial resolution
for detecting short-lived particles like charmed hadrons.
A high precision in vertex reconstruction allows one to measure
the charged particle multiplicities accurately in a high track
density environment. In this paper, the preliminary results of the analysis of the pilot run data are presented.