Amaranda and Bartolo consume only two goods, X and Y. They can trade only with each other and there is no production. The total endowment of good X equals the total endowment of good Y. Amaranda's utility function is U(xA, yA) = max{xA, yA} and Bartolo's utility function is U(xB, yB) = max{xB, yB}. In an Edgeworth box for Amaranda and Bartolo, the set of Pareto optimal allocations is?