You know that Tear is a
perverse girl. She often set some problems for Like.

One day, She fouled the paper with ink. Now, Tear wanted Like to
find the maximum distance between these ink drops for her. Could you help donsie Like?

**Input**

The first line of the input is a positive integer T(T < 30). T is the number
of the test cases followed. For each testcase, first
line contains one integer N(0 < N <＝ 100000). Then N lines followed.
Every line contains two integers (x, y).

Proceed to the end of file.

**Output**

For each testcase, you should output the longest
distance, having 2 digits after radix point.

**Sample Input**

1

4

0 0

1 1

0 1

1 0

Sample Output

1.41

**Author:** *liu** like*