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

const int MAXN = 1000005;

int n, c, l, r, mid, ans;
int a[MAXN];

bool flag(int num)
{
    int cnt = 0;
    for (int i = 0, now = 1; i < n; ++now)
    {
        if (a[now] - a[i] >= num)
        {
            cnt++;
            i = now;
        }
    }
    if (cnt < c)
    {
        return 0;
    }
    return 1;
}

int main()
{
    cin >> n >> c;
    for (int i = 0; i < n; ++i)
    {
        cin >> a[i];
    }
    sort(a, a + n);
    l = 0, r = a[n - 1] - a[0];
    while (l <= r)
    {
        mid = (l + r) >> 1;
        if (flag(mid))
        {
            l = mid + 1;
            ans = mid;
        }
        else
        {
            r = mid - 1;
        }
    }
    cout << ans;
    return 0;
}