Q.10 Firms A and B can upgrade to a new accounting system or stick to the old accounting system. The firms make the choice simultaneously and without colluding. If both firms upgrade, their profits are given by -2 each. If both firms stick to the old system, their profits are given by O each. If one firm upgrades and other firm does not, the profit of the firm which upgrades is 1 and the profit of the firm which does not upgrade is -1. The number of (pure strategy) Nash equilibrium is