  We identify the formulas of Buryak and Okounkov for the n-point functions of
the intersection numbers of psi-classes on the moduli spaces of curves. This
allows us to combine the earlier known results and this one into a principally
new proof of the famous Witten conjecture / Kontsevich theorem, where the link
between the intersection theory of the moduli spaces and integrable systems is
established via the geometry of double ramification cycles.
