Robert Lipshitz has the nicest formula, described in Corollary 4.3 of this paper:

Robert Lipshitz, "A cylindrical reformulation of Heegaard Floer homology", Geometry & Topology 10 (2006) 955–1096, DOI: 10.2140/gt.2006.10.955, arXiv: math.SG/0502404

At this stage, I would not worry so much about the proof of the formula, although it's also not so bad.

Robert Lipshitz has the nicest formula, described in Corollary 4.3 of this paper:

• Robert Lipshitz, A cylindrical reformulation of Heegaard Floer homology, Geometry & Topology 10 (2006) 955–1096, DOI: 10.2140/gt.2006.10.955, arXiv:math/0502404.

At this stage, I would not worry so much about the proof of the formula, although it's also not so bad.