#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
const int N =100010;
int n,m;
int a[N];
bool check(int mid){
int pre=a[0];
int sum=1;
for(int i=1;i<n;i++){
if(a[i]-pre>=mid){
sum++;
pre=a[i];
}
}
if(sum>=m) return true;
else return false;
}
int main(){
cin>>n>>m;
for(int i=0;i<n;i++) scanf("%d",&a[i]);
sort(a,a+n);
int l=0,r=1e9;
while(l<r){
int mid=(l+r+1)/2;
if(check(mid)) l=mid;
else r=mid-1;
}
cout<<l<<endl;
return 0;
}