#include<cstdio>

 #include<iostream>

 #include<string.h>

 #include<algorithm>

 #include<math.h>

 #include<stdbool.h>

 #include<time.h>

 #include<stdlib.h>

 #include<map>

 #include<stack>

 #include<queue>

 #include<vector>

 using namespace std;

 #define clr(x,y)    memset(x,y,sizeof(x))

 #define sqr(x)      ((x)*(x))

 #define rep(i,a,b)  for(int i=(a);i<=(b);i++)

 #define LL          long long

 #define INF         0x3f3f3f3f

 #define A           first

 #define B           second

 const int N=+;

 int n,m,

     a[N];

 bool check(int d)

 {

     int last=;

     for(int i=;i<m;i++) {

         int crt=last+;

         while(crt<n && a[crt]-a[last]<d) {

             crt++;

         }

         if(crt==n) return false;

         last=crt;

     }

     return true;

 }

 void solve()

 {

     sort(a,a+n);

     int lb=,ub=INF;

     while(ub-lb>) {

         int mid=(lb+ub)/;

         if(check(mid)) {

             lb=mid;

         } else {

             ub=mid;

         }

     }

     printf("%d\n",lb);

 }

 int main()

 {

     scanf("%d%d",&n,&m);

     for(int i=;i<n;i++) {

         scanf("%d",&a[i]);

     }

     solve(); 

     return ;

 }