i.4.34 Curvilinear integrals

Condition: Calculate the following curvilinear integral of the 2nd kind, taken along the indicated curves in the direction of increasing parameter: \[ \oint_{C} \frac{(x+y) d x-(x-y) d y}{x^{2}+y^{2}} \] where \( C- \) circle \( x^{2}+y^{2}=a^{2} \), running counterclockwise.