def crossProduct(p1, p2, p3):
    """
    Cross product implementation: (P2 - P1) X (P3 - P2)
    :param p1: Point #1
    :param p2: Point #2
    :param p3: Point #3
    :return: Cross product
    """
    v1 = [p2[0] - p1[0], p2[1] - p1[1]]
    v2 = [p3[0] - p2[0], p3[1] - p2[1]]
    return v1[0] * v2[1] - v1[1] * v2[0]