SP1448 COVER2 - 3D Cover

In the 3D Cartesian coordinate system, there are n cubes.These cubes are all axis-paralleled. What's the volume of the union of these cubes?

There is a single integer m in the very first line of the input, the number of test cases. m blocks follow. For each test, the first line contains a single integer n(1

m lines,each contains a single integer - the answer.