#include <bits/stdc++.h>
using namespace std;

const int N=1e5+5;
int n,c,ans;
int p[N];


int bry(int l,int r,int c)
{
    while(l<=r)
    {
        int mid=l+r>>1;
        int tem=0;int num=0;
        for(int i=1;i<n;i++){
            if(p[i]-p[tem]>=mid){num++;tem=i;}
        }
        if(num>=c){ans=mid;l=mid+1;}
        else r=mid-1;
    }
    cout<<ans;
}
int main()
{
    cin>>n>>c;
    for(int i=0;i<n;i++)cin>>p[i];
    sort(p,p+n);
    bry(0,1e9+5,c);


return 0;}