#include <cstdio>

 #include <iostream>

 #include <algorithm>

 #define max(x, y) ((x) > (y) ? (x) : (y))

 #define N 1000001

 int n, m, ans, maxn;

 int a[N];

 inline int read()

 {

     int x = , f = ;

     char ch = getchar();

     for(; !isdigit(ch); ch = getchar()) if(ch == '-') f = -;

     for(; isdigit(ch); ch = getchar()) x = (x << ) + (x << ) + ch - '';

     return x * f;

 }

 inline bool check(int x)

 {

     int i, now = , sum = ;

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

         if(a[i] - a[now] >= x)

         {

             sum++;

             now = i;

         }

     return sum >= m;

 }

 int main()

 {

     int i, j, x, y, mid;

     n = read();

     m = read();

     for(i = ; i <= n; i++) a[i] = read(), maxn = max(a[i], maxn);

     std::sort(a + , a + n + );

     x = , y = maxn;

     while(x <= y)

     {

         mid = (x + y) >> ;

         if(check(mid)) ans = mid, x = mid + ;

         else y = mid - ;

     }

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

     return ;

 }