#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int a[n + 1];
  for (int i = 1; i <= n; i++) cin >> a[i];
  int ans = 1000;
  for (int i = 2; i < n; i++) {
    int max = a[i + 1] - a[i - 1];
    for (int j = 1; j < n; j++) {
      if (j != i - 1 && j != i) {
        if (max < a[j + 1] - a[j]) max = a[j + 1] - a[j];
      }
    }
    if (ans > max) ans = max;
  }
  cout << ans;
}
