Crossword puzzles use a grid of black and white squares that traditionally obeys the following rules.

1. Every word (a string of consecutive white squares in a row or column) has at least 3 letters (white squares). Each letter is part of a word going across and a word going down, and there are no 2-letter words.
2. The grid is symmetrical. It is the same upside-down.
3. The grid is connected. Between any two white squares, there is a path of white squares that only goes horizontally and vertically.

What is the most words possible in a crossword puzzle with 15 rows and 15 columns? Find a 15*15 crossword grid with the maximum number of words.