The closed curve shown in the figure is described by
$r=1+\cos \theta,$ where $r=\sqrt{x^{2}+y^{2}} ; x=r \cos \theta, y=r \sin \theta$
The magnitude of the line integral of the vector field $ F=-y \hat{\imath}+x \hat{\jmath}$ around the closed curve is __________(Round off to $2$ decimal places).
