#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstdlib>
using namespace std;

int arr[100001], N, C;

bool pos(int len) {
	int prev = arr[1], cow = 1;
	for (int i = 2; i <= N && cow < C; i++)
		if (arr[i] - prev >= len)
			prev = arr[i], cow++;

	return cow == C;
}

int main ()
{
	scanf("%d", &N);
	scanf("%d", &C);

	for (int i = 1; i <= N; i++)
		scanf("%d", &arr[i]);

	sort(arr, arr+1+N);

        // Binary Search
	int high = arr[N], low = 0;
	while(high - low > 1) {
		int middle = (high + low)/2;
		pos(middle)? low=middle : high=middle;
	}

	cout << low << endl;
	return 0;
}