本题写了一个EE3的产品描述，是四维的。确实很难想像清楚。我们这样想就行。它有四个坐标，每一维都可以放上一个立方体，边长为1.然后就是怎么判断是否Inconsistent，有两种情况：1），如题上举的例子，ID为1的在x2坐标上前面是3，那么ID为3的在X2坐标的后面应该是1，否则就Inconsistent。-We usually think that there are three geometric dimensions　the fourth dimension is usually time. However, the Association for Customizing Machines (ACM) has to deal with four geometrical dimensions for their strange customer EE3 who needs to pack four dimensional products into perpendicular parallelepipeds before shipping them to the newly emerged market niche just on the outskirts of the Milky Way.

Each of EE3 products consists of a number of unit 4D cubes that are glued together at their faces. A face of a 4D cube is a 3D cube and each 4D cube has 8 such faces. The picture on the left shows a 4D cube projected into a plane with the four principal, orthogonal axes shown. It takes a bit of effort to stretch our imagination and see the faces of a 4D cube in such a projection. The pictures below try to illustrate how the two faces along each of the four axes are situated in 4D. Again, using just the planar projection it is not so easy to illustrate and takes some effort to see. But we