#include <bits/stdc++.h>
using namespace std;

#define SZ(a) (int)a.size()
#define ALL(a) a.begin(), a.end()
#define FOR(i, a, b) for (int i = (a); i<(b); ++i)
#define RFOR(i, b, a) for (int i = (b)-1; i>=(a); --i)
#define MP make_pair
#define PB push_back
#define F first
#define S second

typedef long long LL;
typedef pair<int, int> PII;
typedef vector<int> VI;

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	int n;
	cin >> n;
	vector<LL> h(n);
	LL ans = 0;
	FOR (i, 0, n)
		cin >> h[i];
	FOR (i, 1, n - 1)
	{
		int j = i - 1;
		int k = i + 1;
		if (h[j] <= h[i] && h[i] >= h[k])
		{
			while (j > 0 && h[j - 1] <= h[j]) j--;
			while (k < n - 1 && h[k + 1] <= h[k]) k++;
			ans = max(ans, min(h[i] - h[j], h[i] - h[k]));
		}
	}
	cout << ans << '\n';
	return 0;
}