def max_or(a, b, c, d, w):
        """
        Upper bound of result of ORing 2-intervals.

        :param a: Lower bound of first interval
        :param b: Upper bound of first interval
        :param c: Lower bound of second interval
        :param d: Upper bound of second interval
        :param w: bit width
        :return: Upper bound of ORing 2-intervals
        """
        m = (1 << (w - 1))
        while m != 0:
            if (b & d & m) != 0:
                temp = (b - m) | (m - 1)
                if temp >= a:
                    b = temp
                    break
                temp = (d - m) | (m - 1)
                if temp >= c:
                    d = temp
                    break
            m >>= 1
        return b | d