  We consider the non-linear massive gravity as a theory of a number of
St\"uckelberg scalar fields minimally coupled to the Einstein-Hilbert gravity
and argue that the counting of degrees of freedom can be done for scalar theory
and gravity separately. In this paper we investigate the system with only two
St\"uckelberg scalar fields. In this case we find the analytic expression for
the determinant of the kinetic matrix of the scalar field Lagrangian and
perform the full constraint analysis. In 1+1 space-time dimensions the theory
corresponds to the full non-linear massive gravity, and this determinant
vanishes identically. In this case we find two first-class constraints, and
present the corresponding gauge symmetry of the theory which eliminates both
scalar degrees of freedom. In 3+1 dimensions the determinant of the kinetic
matrix does not vanish identically and, for generic initial conditions, both
scalar fields are propagating.
