Crossword puzzle is a table, in which white squares represent empty places for the letters, while black squares denote invalid positions. A word must be written in the white squares vertically and/or orizontally. There are specifications for the vertical and horizontal words as well. Closed squares are those squares which are members of one word only. The boundary cells count as black squares

Task

Design a template which detects the closed squares.

Given: static binary image P Input:

U(t) = P Initial state: X(0) = 0 Boundary conditions:

1 Output: Y(t) Y() = a binary image,

which represents the closed squares.