A MST Problem

It is just a mining spanning tree ( 最小生成树 ) problem, what makes you a little difficult is that you are in a 3D space.

For each test case, output a line with the answer, which should accurately rounded to two decimals .

2
2
1 1 0
2 2 0
3
1 2 3
0 0 0
1 1 1

1.41
3.97