#include <bits/stdc++.h>
using namespace std;
const long long N = 2e3 + 10, INF = 1e9 + 10;
long long dp[N][2], a[N], n, k;
inline bool check(long long x) {
  for (long long i = 1; i <= n; i++) dp[i][0] = i - 1;
  for (long long i = 1; i <= n; i++)
    for (long long j = i - 1; j; --j) {
      if (a[i] + (i - j) * x < a[j] || a[i] - (i - j) * x > a[j]) continue;
      dp[i][0] = min(dp[i][0], dp[j][0] + i - j - 1);
    }
  for (long long i = n; i; i--) dp[i][1] = n - i;
  for (long long i = n; i; i--)
    for (long long j = i + 1; j <= n; ++j) {
      if (a[i] + (j - i) * x < a[j] || a[i] - (j - i) * x > a[j]) continue;
      dp[i][1] = min(dp[i][1], dp[j][1] + j - i - 1);
    }
  for (long long i = 1; i <= n; i++)
    if (dp[i][0] + dp[i][1] <= k) return 1;
  return 0;
}
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> k;
  if (k == n) return cout << "0", 0;
  for (long long i = 1; i <= n; i++) cin >> a[i];
  long long lo = 0, hi = 2e9 + 5;
  while (hi - lo > 0) {
    long long mid = (hi + lo) / 2;
    if (check(mid))
      hi = mid;
    else
      lo = mid + 1;
  }
  cout << lo;
  return 0;
}
