If a zero- sum two- person game has a saddle point corresponding to the ith row and the jth column of the payoff matrix and another corresponding to the kth row and the lth column, show that

(a) There are also saddle points corresponding to the ith row and the lth column of the payoff matrix and the kth row and the jth column;

(b) The payoff must be the same for all four saddle points.