#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <cstring>
#include <string>
#include <algorithm>
#include <cmath>
#include <vector>
#include <queue>
#include <stack>
#include <deque>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <functional>

typedef long long int ll;
using namespace std;
#define INF 1234567890
#define N 200000

const int LIMIT = 1e+9;
ll n, c;
ll value[200005];

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

	cin >> n >> c;

	for (int i = 0; i < n; i++) {
		cin >> value[i];
	}
	sort(value, value + n);
	ll left = 0, right = value[n - 1] - value[0];
	ll res = 0;

	while (left <= right) {
		ll mid = (left + right) / 2;
		ll count = 1;
		ll location = value[0];

		for (int i = 1; i < n; i++) {
			if (value[i] - location >= mid) {
				count++;
				location = value[i];
			}
		}

		if (count < c) {
			right = mid - 1;
		}
		else {
			res = max(res, mid);
			left = mid + 1;
		}
	}

	cout << res;

	return 0;
}