1203  Union
Time Limit : 5 Second
Memory Limit : 128 MB
Submission: 239
Solved: 38
 Description
 Given two balls in 3D space, you are asked to calculate the volume of their union, ie the total volume.
 Input
 There multiple cases:
Each case contains two lines:
1stline: x1, y1, z1, r1
2ndline: x2, y2, z2, r2
Each line specifies the coordinate and the radius of a ball.
The input file termitates with EOF.
All the data in the input are integers in [20, 20].
 Output
 A single number: the volume of the union with a precision of 3 numbers after the decimal point.
 sample input

0 0 0 1 0 0 2 1
 sample output

8.378
 hint
 source
 Isun