/*
    Author:zeke
    
    pass System Test!
    GET AC!!
*/
#include <iostream>
#include <queue>
#include <vector>
#include <iostream>
#include <vector>
#include <string>
#include <cassert>
#include <algorithm>
#include <functional>
#include <cmath>
#include <queue>
#include <set>
#include <stack>
#include <deque>
#include <map>
#include <iomanip>
#include <utility>
#include <stack>
using ll = long long;
using ld = long double;
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define all(x) (x).begin(), (x).end()
#define rep3(var, min, max) for (ll(var) = (min); (var) < (max); ++(var))
#define repi3(var, min, max) for (ll(var) = (max)-1; (var) + 1 > (min); --(var))
#define Mp(a, b) make_pair((a), (b))
#define F first
#define S second
#define Icin(s) \
    ll(s);      \
    cin >> (s);
#define Scin(s) \
    ll(s);      \
    cin >> (s);
template <class T>
bool chmax(T &a, const T &b)
{
    if (a < b)
    {
        a = b;
        return 1;
    }
    return 0;
}
template <class T>
bool chmin(T &a, const T &b)
{
    if (b < a)
    {
        a = b;
        return 1;
    }
    return 0;
}
typedef pair<ll, ll> P;
typedef vector<ll> V;
typedef vector<V> VV;
typedef vector<P> VP;
ll mod = 1e9 + 7;
ll INF = 1e18;

V vec;
ll n, k;
bool judge(ll x){
    ll cnt = 0;
    ll prev = 0;
    while(1){
        ll f = lower_bound(all(vec), prev+x) - vec.begin();
        if(f==n){
            cnt++;
            break;
        }
        cnt++;
        prev = vec[f];
    }
  //  cout<<x<<" "<<cnt<<endl;
    return cnt <= k;
}
int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    
    cin >> n>>k;
    vec.resize(n);
    rep(i, n) cin >> vec[i];
    sort(all(vec));
    ll Max = 1e18;
    ll Min = 0;
    rep(i,100){
        ll Half=(Max+Min)/2;
        if(judge(Half)){
            Max = Half;
        }else{
            Min = Half;
        }
    }
    cout << Max << endl;
}