Sam can swim at a speed of 2 meters per second in still water. However, when swimming in a river with a current that flows at 1 meter per second, his effective speed downstream (with the current) increases by the speed of the current, while his effective speed upstream (against the current) decreases by the speed of the current. If Sam swims 200 meters downstream and then returns the same distance upstream, how long does the entire swim take? Let's think step by step and output the final answer within \boxed{}.
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