#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main()
{
	int n,k;
	cin>>n>>k;
	vector<int> a;
	for(int i=0;i<n;++i)
	{
		int b;
		cin>>b;
		a.push_back(b);
	}
	sort(a.begin(),a.end());
	int p=0;
	int q=k-1;
	int ans=a[q]-a[p];
	while(q!=n)
	{
		if(a[q]-a[p]<ans)
			ans=a[q]-a[p];
		++p;
		++q;
	}
    cout<<ans<<endl;
}