#include "stdafx.h"

#include <iostream>
#include <cstdlib>


using namespace std;

int main()
{
    int n, temp, d, min, max, len, s, res;
    int  a[5000], b[5000];
    res = 0;
    cin >> n;
    //cout << endl;
    for (int i = 0; i < n; ++i)
    {
        cin >> a[i];
    }

    for (int d = 1; d <= n; ++d)
    {
        for (int start = 0; start <= d - 1; ++start)
        {
            len = 0;
            s = 0;
            //min = max = 0;
            for (int i = start, j = 0; i < n; i += d, ++j)
            {
                ++len;
                b[j] = a[i];
            }
            min = max = b[0];
            for (int i = 0; i < len; ++i)
            {
                s += b[i];
                if (s > max)
                {
                    max = s;
                }
                if (s < min)
                {
                    min = s;
                }
            }
            if (max - min > res)
            {
                res = max - min;
            }


        }
    }
    cout << res;
    system("pause");
    return 0;
}