Time Limit: 5 Seconds
Memory Limit: 32768 KB
Have you ever played quoit in a playground? Quoit is a game in which flat rings
are pitched at some toys, with all the toys encircled awarded.
In the field of Cyberground, the position of each toy is fixed, and the ring
is carefully designed so it can only encircle one toy at a time. On the other
hand, to make the game look more attractive, the ring is designed to have the
largest radius. Given a configuration of the field, you are supposed to find
the radius of such a ring.
Assume that all the toys are points on a plane. A point is encircled by the
ring if the distance between the point and the center of the ring is strictly
less than the radius of the ring. If two toys are placed at the same point,
the radius of the ring is considered to be 0.
The input consists of several test cases. For each case, the first line contains
an integer N (2 <= N <= 100,000), the total number of toys in the field.
Then N lines follow, each contains a pair of (x, y) which are the coordinates
of a toy. The input is terminated by N = 0.
For each test case, print in one line the radius of the ring required by the
Cyberground manager, accurate up to 2 decimal places.
Author: CHEN, Yue
Source: Zhejiang Provincial Programming Contest 2004