"Triple A doesn't always match retained earnings, for a variety of reasons, most common of which is that some transactions can reduce retained earnings below zero, but can't reduce AAA below zero."

You could go back to the inception of the corporation and figure out when and why each component of the discrepancy arose, but the cost of that should be borne by the curious shareholder.

Also, it doesn't make a bit of difference for an S-corp that's always been an S-corp.