package Greedy;
import java.util.*;
import java.io.*;
/*
* @author -- rajatgoyal715
*/
public class MaxMin {
public static void main(String[] args) throws NumberFormatException, IOException {
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
int N = Integer.parseInt(in.readLine());
int K = Integer.parseInt(in.readLine());
int[] list = new int[N];
for(int i = 0; i < N; i ++)
list[i] = Integer.parseInt(in.readLine());
int unfairness = Integer.MAX_VALUE;
Arrays.sort(list);
int temp;
for(int i=0;i<=N-K;i++){
temp = list[i+K-1]-list[i];
if(temp