#include <bits/stdc++.h>
#pragma GCC optimize(2)
using namespace std;
#define int long long
//fixed << setprecision()
const int length = 1e6 + 5;
int n;
int a[length];
int ans = 0;



signed main()
{
	ios::sync_with_stdio(false);
	cin >> n;
	for(int i = 1;i <= n;i++)
	{
		cin >> a[i];
	}
	ans = max(a[n] - a[1], a[1] - a[n]);
	for(int i = 1;i <= n - 1;i++)
	{
		ans = max(ans, a[n] - a[i]);
	}
	for(int i = n;i >= 2;i--)
	{
		ans = max(ans, a[i] - a[1]);
	}
	cout << ans << endl;
	return 0;
}