#include <bits/stdc++.h>
using namespace std;

#define llj(a,b,c) for (int (a) = (b); (a) < (c); (a)++)
#define lli(a,b) llj(i,a,b)
#define lll(i, x) llj(i, 0, x)
#define fori(x) lll(i, x)
#define forj(x) lll(j, x)
#define fork(x) lll(k, x)

#define all(X) (X).begin(), (X).end()
#define ever ;;
#define fe(x, C) for (auto& x : (C))
#define INF ((int) 1e9+10)

#define LINF ((ll) 1e18 + 10)
#define pb push_back
#define mp make_pair
#define ms(arr,val) memset(arr , val , sizeof(arr))
#define rint(x) scanf("%d", &(x))
#define rlong(x) scanf("%lld", &(x))
#define nrint(x) int x; rint(x);
#define nrlong(x) long long x; rlong(x);
#define rfloat(x) scanf("%lf", &(x))
#define endl "\n"
#define trace(X) cout << (X) << endl;
#define trace2(X,Y) cout << (X) << ' ' << (Y) << endl;
#define trace3(X,Y,Z) cout << (X) << ' ' << (Y) << ' ' << (Z) << endl;
#define trace4(X,Y,Z,A) cout << (X) << ' ' << (Y) << ' ' << (Z) << ' ' << (A) << endl;
#define tp(X) trace2(X.first ,X.second)
#define vi vector<int>
#define vvi vector<vector<int> >
#define pvi(a) fe(thing ,a) cout << thing << ' '; cout << "\n";

typedef long long ll;
typedef pair<int,int> pii;
#define sz(A) ((int)A.size())
#define x first
#define y second
#define read_speed ios::sync_with_stdio(false); cin.tie(0)
#define LINE cout << endl << "--------------------------" << endl
/*--------------------------THE END---------------------------------*/


int n,k;

vector<int> x;

int Check(int dist)
{

  int needed = 0;

  int current = 0;

  while (current < n)
  {
    //cout << current << endl;
    int cityIndex = upper_bound(all(x), x[current] + dist) - x.begin() - 1;

    int lastIndex = upper_bound(all(x), x[cityIndex] + dist) - x.begin() - 1;

    current = lastIndex + 1;
    needed++;

    //trace3(cityIndex, lastIndex, current);
  }



  return needed <= k;
}

int BinarySearch()
{
  int lo = 0, hi = 1e9;

  while (lo < hi)
  {
    int mid = (lo + hi) / 2;

    if (Check(mid))
    {
      hi = mid;
    }
    else
    {
      lo = mid + 1;
    }
  }

  return lo;
}

int main()
{
  // freopen("test.txt", "r", stdin);

  cin >> n >> k;

  int temp;

  fori(n)
  {
    cin >> temp;
    x.push_back(temp);
  }

  sort(all(x));

  cout << BinarySearch() << endl;

  //cout << Check(2) << endl;

}