public static long getMaxRectangleSum() {
		int ROWS = m.length, COLS = m[0].length;
		long[] comp = new long[ROWS];
		long maxArea = 0;
		for (int left = 0; left < COLS; left++) {
			Arrays.fill(comp, 0);
			for (int right = left; right < COLS; right++) {
				for (int r = 0; r < ROWS; r++)
					comp[r] += m[r][right];
				long height = kadane(comp);
				maxArea = Math.max(maxArea, height * (right - left + 1));
			}
		}
		return maxArea;
	}