#include<bits/stdc++.h>
using namespace std;
int a[100000005];
int main(){
	int n,m,minn=100000000;
	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;i++){
		if(i+m<=n+1){
			minn=min(minn,a[i+m-1]-a[i]);
		}
	}
	cout<<minn;
	return 0;
}