The value of \(\oint\limits_{\rm{C}} {{\rm{[(cos}}} \,{\rm{x}}\,{\rm{sin}}\,{\rm{y}}\,{\rm{ - xy)dx + sin}}\,{\rm{x}}\,{\rm{cos}}\,{\rm{y}}\,{\rm{dy]}}\) where C is the circle x² + y² = 1, is: