Guessing Aces and Kings

A pile holds 3 aces and 3 kings, shuffled uniformly at random. The cards are turned over one at a time. Before each card you call out a rank, and you earn 1 dollar for every correct call. You remember every card already turned over and you play optimally.

How much do you expect to earn over the 6 cards? Answer format: round to 2 decimal places.