In the graph above, the marginal private cost (MPC) and marginal social cost (MSC) of robot production for the factory positioned next to a dormitory for nurses who work nightshifts are presented. The market for robots is competitive and the market price is $340. The initial output is 120. But now the government requires the factory to compensate the nurses for the external cost caused by each robot it produces, so that the output will drop to the efficient level of 80. How much will the total compensation be?

(Do not include the dollar sign in your answer)