#include<iostream>
#include<algorithm>
#define N 100010
using namespace std;
int a[N];
int n, c;
bool Judge(int x)
{
    int tmp = 1;
    int cnt = 1;
    for(int i = 2; i <= n; i++)
    {
        if(a[i] - a[tmp] >= x)
            cnt++;
            tmp = i;
    }
    if(cnt >= c)
        return true;
    else
        return false;
}
int main()
{
    cin >> n >> c;
    for(int i = 1; i <= n; i++)
        cin >> a[i];
    sort(a + 1, a + n + 1);
    int l = 0, r = a[n] - a[1], mid;
    while(l < r)
    {
        mid = l + (r - l) / 2;
        if(Judge(mid))
            l = mid + 1;  
        else
            r = mid;
    }
    cout << l;
    return 0;
}