sentences:  Further layers are then stacked on top.To use a precomputed table of size "n" ("n" = 256 is typical), one chooses "x"1 such that "x""n" = 0, meaning that the top box, layer "n" − 1, reaches the distribution's peak at (0, "f"(0)) exactly.Layer "i" extends vertically from "y""i" to "y""i"+1, and can be divided into two regions horizontally