The ACM/ICPC team has bought n wifi APs. And the APs have a special feature called Wifi

Relay which means if two APs’ signal can cover each other, then they can work like a single wifi

AP.

Each AP can cover a round area, the radius of which is r.

In a programming contest, GSS set up n APs, and the i-th AP is placed at (x i ,y i ). Then GSS

use the Wifi Relay to let all the APs work like a single AP that every one can access the system

without being interrupted.

Then GSS has to set all the radius each APs can cover to r. To save pover, GSS has to get the

minimal r he should set, can you help him to do that?

The first line of input is an integer n. (2 ≤ n ≤ 10 4 )

The following n lines, the i-th one of them contains two integers (x i ,y i ), the position GSS place

i-th AP. (0 ≤ x i ,y i ≤ 10 8 )

Output one integer, the minimal r GSS should set. Your answer will be considered as correct if

the relative or absolute error is less than 10 −9

2017 Wuhan University Programming Contest