#include <iostream>

 #include <vector>

 #include <math.h>

 #include <algorithm>

 using namespace std;

 /*

 Sample Input

 5 3

 1

 2

 8

 4

 9

 Sample Output

 3

 */

 vector<int> v;

 int n, m;

 bool check(int d)

 {

     int mm=m-;

     int lastselect = v[];

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

         if (v[i] - lastselect >= d) {

             mm--;

             lastselect = v[i];

             if (mm == )

                 return false;

         }

     }

     return true;

 }

 int main()

 {

     cin >> n >> m;

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

         int t; cin >> t;

         v.push_back(t);

     }

     if (m == ) {

         printf("0\n");

         return ;

     }

     sort(v.begin(), v.end());

     //距离的极端取值k

     int l = ; int r = v.back();

     while (l<r) {

         int mid = l + r >> ;

         if (check(mid)) r = mid;

         else {

             l = mid + ;

         }

     }

     cout << r- << endl;

     return ;

 }