#include <cstring>
#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <queue>
#include <cstdlib>
#include <ctime>
#include <cassert>

#define pii pair<ld, ld>

#define pb push_back
#define mp make_pair

#define x first
#define y second

using namespace std;

typedef unsigned long long ull;
typedef long long ll;
typedef long double ld;

const int MXN = 1e5 * 2 + 1;
const int TMXN = 1e5 * 8 + 1;
const int INF = 1e9 + 7;
const ll INFL = 1e18;

ll n, m, t[TMXN], l, r, d[TMXN], res, c, maxk, ind = 1, ans, k;
ll a[MXN], two = 1, b[MXN];
bool chec(int x){
     for(int i = 2; i <= n; i++){
        if(a[i] - a[ind] >= x){
            ind = i;
            ans ++;
        }
     }
     if(ans >= k){
        return true;
     }
     else{
        return false;
     }
}
int main(){
    freopen("cows.in", "r", stdin);
    freopen("cows.out", "w", stdout);
    cin >> n >> k;
    for(int i = 1; i <= n; i++){
        cin >> a[i];
    }
    l = 0;
    r = INF;
    while(r - l > 1){
        ll mid = (l + r) / 2;
        ind = 1;
        ans = 1;
        if(chec(mid)){
            l = mid;
            maxk = max(maxk, mid);
        }
        else{
            r = mid;
        }
    }
    cout << maxk;
    return 0;
}