Physics · Electrostatics

Two charges +q and -q are placed at points A and B respectively, which are at a distance 2L apart. C is the midpoint of A and B. The work done in moving a charge +Q along a semicircle CSD (W1) to a point D (at distance 2L from C on the line AB extended) and along the line CBD (W2) to the same point D are equal since electrostatic force is conservative. If the final distance of D from the center C is 2L, what is the work done?