import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    static long largestValue(int[] A) 
    {
        int n=A.length;
        long max=Integer.MIN_VALUE;
        for(int i=0;i<n;i++)
        {
            long sum=0;
            long ps=0;
            for(int j=i;j<n;j++)
            {
                sum+=ps*A[j];
                ps+=A[j];
                max=Math.max(max,sum);
            }
        }
        return max;
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int[] A = new int[n];
        for(int A_i = 0; A_i < n; A_i++){
            A[A_i] = in.nextInt();
        }
        long result = largestValue(A);
        System.out.println(result);
        in.close();
    }
}