#include<bits/stdc++.h>
using namespace std;
int n,m,a[1000001],mid,ans;
int check(int x)
{
	int num=1,last=a[1];
	for (int i=2;i<+n;i++)
	{
		if (a[i]-last>=x)
		{
			last=a[i];
			num++;
		}
	}
	return num;
}
int main()
{
	cin>>n>>m;
	for (int i=1;i<=n;i++)
	cin>>a[i];
	sort(a+1,a+n+1);
	int l=1,r=1e9;
	while(l<=r)
	{
		mid=(r-l)/2+l;
		if (check(mid)>=m)
		{
			l=mid+1;
			ans=mid;
		}
		else
		{
			r=mid-1;
		}
	}
	cout<<ans;
	return 0;
}