1714  Fighting and Fighting
Time Limit : 8 Second
Memory Limit : 128 MB
Submission: 28
Solved: 4
 Description
After becoming king of SanSanQi, Jia want to attack SiSiBa country because he think the king of SiSiBa is ugly. But he has to go through a sea, and the following picture is the sea. SanSanQi is on the left, SiSiBa is on the right. There are many barriers in the sea that don’t allow ship to pass, and strangely enough, their ship is circle. You know, he need to send more people to occupy SiSiBa. Of course, more greater the ship more people. Now Jia want to know the maximum diameter of the ship.
 Input
The input consists of multiple test cases
For each case the first line contains one integer N (1 <= N <= 3,000) which means the number of barriers. The second line contains one integer M which mean the upper boundary. then for each line of next n lines contains four integers x1, y1, x2, y2 which mean the coordinate of each barrier (x1, y1) and (x2, y2) (0 <= M, x1, x2 y1, y2 <= 1000,000,000).
 Output
For each case, output the maximal value of Jia’s warship. (keep two decimal)
 sample input

1 5 1 1 1 4
 sample output

1.00
 hint
 source
 baojia