Chern-Osserman type equality for complete surfaces in Rn

We obtain a Chern-Osserman type equality of a complete immersed surface in Euclidean space, provided the L2-norm of the second fundamental form is finite. Also, by using a monotonicity formula, we prove that if the L2-norm of mean curvature of a noncompact surface is finite, then it has at least quadratic area growth.