#include
using namespace std;
const int N = 3e5 + 1;
int a[N];
int n , k;
int dem(int x){
int de = 0;
for (int i = 2; i <= n; i++)
if (a[i] - a[i - 1] <= x)
de++ , i++;
return de;
}
int main(){
cin >> n >> k;
for (int i = 1; i <= n; i++)
cin >> a[i];
sort(a + 1,a + 1 + n);
int L = 0 , R = 1e9 , res = 1e9;
while (L <= R){
int mid = (L + R) >> 1;
if (dem(mid) >= k)
{
res = mid;
R = mid - 1;
}
else L = mid + 1;
}
cout << res;
return 0;
}