Description

The residents of Wonderland have decided to host a regional programming competition. The judging committee is entirely voluntary and has pledged to organize the fairest competition in history. They decided to connect the contestants' computers in a star topology, linking them all to a single central server. To organize this perfectly fair competition, the chair of the judging committee proposed placing all the contestants' computers at equal distances around the server.

To purchase the network cables, the judging committee contacted a local network solutions provider, requesting a certain number of network cables of equal length. The committee hopes the cables can be as long as possible so that the contestants can be placed as far apart as possible.

The cable supervisor at the company took on this task. He knows the length of each cable in stock (accurate to centimeters) and can cut the cables to the required length (also accurate to centimeters) once he is told what that length should be.

However, this time, the required cable length is unknown, leaving the cable supervisor at a loss.

You need to write a program to help the cable supervisor determine the maximum possible length of the cables such that, when the stock cables are cut to this length, the specified number of cables can be obtained.

Input Format

The first line contains two integers, N and K, separated by a single space. N (1 ≤ N ≤ 10,000) is the number of cables in stock, and K (1 ≤ K ≤ 10,000) is the number of cables needed.
The next N lines each contain a number representing the length of each cable in stock (in meters).
All cable lengths are at least 1m and at most 100km. All lengths in the input are accurate to centimeters, i.e., with exactly two decimal places.

Output Format

The maximum length (in meters) of the cables that the supervisor can cut from the stock to obtain the specified number of cables. The length must be accurate to centimeters, i.e., with exactly two decimal places.
If it is impossible to obtain the specified number of cables with lengths of at least 1cm, the output must be "0.00" (without quotes).

4 11
8.02
7.43
4.57
5.39

2.00