#include <iostream>
#include <algorithm>
#include <map>
#include <set>
#include <cassert>
#include <vector>
#include <cmath>
using namespace std;
const int MAXN = 100005;
const int INF = 2000000007;
int dp[MAXN];
int main(int argc, char const *argv[])
{
	int n,k;
	cin>>n>>k;
	vector <int> A(n);
	for (int i = 0; i < n; ++i)
	{
		cin>>A[i];
	}
	int lo = 0, hi = INF, mid;
	while(lo < hi)
	{
		mid = (lo + hi)/2;
		bool ok = false;
		int curr = 1, cmax = 1;
		for (int i = 1; i < n; ++i)
		{
			if(A[i] > A[i-1] + mid)
				curr = 1;
			else
				curr++;
			cmax = max(cmax, curr);
		}
		if(n - cmax <= k)
			hi = mid;
		else
			lo = mid + 1;
	}
	cout<<lo<<"\n";
	return 0;
}