  In this paper the number of ways to glue together several polygons into a
surface of genus $g$ has been investigated. We've given an elementary proof on
the formula for the generating function $\mathbf{C}_g^{[2]}(z)$ of the number
of gluings surface of genus $g$ from two polygons (see also [4]). Moreover,
we've proven a similar formula for gluings surface of genus $g$ from three
polygons. As a corollary, we've proven a direct formula for the number of
gluings torus from three polygons.
