#include <cstdio>

 #include <algorithm>

 const int maxn = ;

 const int maxN = ;

 int N, C;

 int a[maxN];

 using namespace std;

 bool judge(int x) {

     int s = ;

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

         int ctr = s+;

         while (ctr < N && (a[ctr]-a[s] < x)) {

             ctr++;

         }

         if (ctr==N) {

             return false;

         }

         s = ctr;

     }

     return true;

 }

 int main(void)

 {

     scanf("%d%d", &N, &C);

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

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

     }

     sort(a, a+N);

     int l = , u = maxn, mid;

     for (;(u-l)>;){

         mid = (l+u)/;

         if (judge(mid)) {

             l = mid;

         } else {

             u = mid;

         }

     }

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

     return ;

 }