private void drawNumbers(Graphics2D g2d) {
		for (int i=0; i<width; i++) {
			for (int j=0; j<height; j++) {
				if (numbers[i][j] >= 0) {
					if (black [i][j] == null || !black[i][j]) {
						g2d.setColor(Color.black);
					} else {
						g2d.setColor(Color.white);
					}
					g2d.drawString("" + numbers[i][j], i*SIZE + SIZE/2 - FONTSIZE/3, j*SIZE + SIZE/2 + FONTSIZE/2 - 1);
				}
			}
		}
	}