Robbie is playing an interesting computer game. The game field is an unbounded 2-dimensional region. There are N rounds in the game. At each round, the computer will give Robbie two places, and Robbie should choose one of them to put a bomb. The explosion area of the bomb is a circle whose center is just the chosen place. Robbie can control the power of the bomb, that is, he can control the radius of each circle. A strange requirement is that there should be no common area for any two circles. The final score is the minimum radius of all the N circles.
Robbie has cracked the game, and he has known all the candidate places of each round before the game starts. Now he wants to know the maximum score he can get with the optimal strategy.
The first line of each test case is an integer N (2 <= N <= 100), indicating the number of rounds. Then N lines follow. The i-th line contains four integers x1i, y1i, x2i, y2i, indicating that the coordinates of the two candidate places of the i-th round are (x1i, y1i) and (x2i, y2i). All the coordinates are in the range [-10000, 10000].
Output one float number for each test case, indicating the best possible score. The result should be rounded to two decimal places.
1 2 3 4 5 6
2 1 1 1 -1 -1 -1 -1 1 2 1 1 -1 -1 1 -1 -1 1
给定你 N 组炸弹，每组有两个，现要挑选并引爆这其中 N 个炸弹，并且每组需要且只能引爆一个，已知这 2×N 个炸弹的位置，每个炸弹的爆炸半径都是一样的，请你求出一个最大的爆炸半径使得引爆的每个炸弹的爆炸范围不重合。