#include <bits/stdc++.h>

using namespace std;
using LL = long long;

const int N = 100010;

int n, m;
int d[N];

bool check(LL mid)
{
    int cnt = 1;
    for (int i = 1, j = 0; i < n; i ++)//i代表当前这头牛,j代表前一头牛
        if (d[i] - d[j] >= mid) cnt ++, j = i;

    return cnt >= m;
}

int main()
{
    ios::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);

    cin >> n >> m;
    for (int i = 0; i < n; i ++) cin >> d[i];
    sort(d, d + n);

    LL l = 1, r = 1e9;
    while (l < r)
    {
        LL mid = l + r + 1 >> 1;
        if (check(mid)) l = mid;
        else r = mid - 1;
    }

    cout << l << '\n';

    return 0;
}