Chern number identities on compact complex surfaces and applications

In this paper, we establish Chern number identities on compact complex surfaces. As an application, we prove that if $(M,g)$ is a compact Riemannian four-manifold with constant scalar curvature and admits a compatible complex structure $J$ such that the complexified Ricci curvature is a non-positive $(1,1)$ form, then $M$ is a Kähler surface.