#include<bits/stdc++.h>
using namespace std;
int n,x,m,a[1000000],sum[1000000],minn=0x3f3f3f3f;
int main(){
	cin>>n>>m;
	for(int i=1;i<=n;i++)
		cin>>a[i];
	sort(a+1,a+n+1);
	
	for(int i=1;i<=n-m;i++){
		minn=min(minn,a[i+m-1]-a[i]);
	}
	cout<<minn;
	return 0;
}