#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int max_gain(const vector<int> &a, 
             const int l, const int r, 
             int &min_a, int &max_a)
{
    if (r - l < 1) {
        min_a = a[l];
        max_a = a[l];
        return 0;
    }

    int mid = l + (r - l) / 2;

    int min_l, max_l;
    int res_l = max_gain(a, l, mid, min_l, max_l);

    int min_r, max_r;
    int res_r = max_gain(a, mid + 1, r, min_r, max_r);

    min_a = min(min_l, min_r);
    max_a = max(max_l, max_r);

    return max({ res_l, res_r, max_r - min_l });
}

int max_gain(const vector<int> &a)
{
    int min, max;
    return max_gain(a, 0, a.size() - 1, min, max);
}

int main(void)
{
    int n;
    cin >> n;

    vector<int> a(n);
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }

    cout << max_gain(a) << endl;

    return 0;
}