The folk theorem for infinitely repeated games with imperfect public monitoring implies that for a general class of games, nearly efficient payoffs can be supported in perfect public equilibrium (PPE), provided the monitoring structure is sufficiently rich and players are arbitrarily patient. This paper shows that for stage games in which actions of players interfere strongly with each other, exactly efficient payoffs can be supported in PPE even when the monitoring structure is not rich and players are not arbitrarily patient. The class of stage games we study abstracts many environments including resource sharing.