private boolean marginBuildings(int x, int y, int m) {
	for (int dx = x - m; dx < x + m; dx++) {
	    for (int dy = y - m; dy < y + m; dy++) {
		if (dx > 0 && dy > 0 && buildings[dx][dy] != null) {
		    return true;
		}
	    }
	}
	return false;
    }