Stevie : "Integer sequences, that's my main activity off the pitch. Let's play with them". Great defenders are an asset to any team, just like this guy :

You are given a sequence of positive integers in the form of an array A of size N and a number K. Now, you need to perform a certain procedure over this sequence that is as follows :

1. For each pair $(i,j)$, where $1 \le i < j \le N$ store in a list $|A[i]-A[j]|$

2. Sort this list in non-decreasing order

3. Print the $K^{th}$ element of this list (1 indexed)

Note that X denotes the absolute value of any integer X

You need to perform the following procedure and print to output whatever it leads to. Can you do it ?

input Format :

The first line contains 2 space separated integers N and K respectively. The next line contains N space separated integers, where the $i^{th}$ integer denotes $A[i]$.

Output Format :

Print the required answer on a single line.

Constraints :

$2 \le N \le 200,000$

$1 \le A[i] \le 10^9$ , where $1 \le i \le N$

$1 \le K \le (N \times (N-1))/2$