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

public class Solution {

    static long largestValue(int[] A) {
        // Return the largest value of any of A's nonempty subarrays.
        long max=A[0];
        long sum_here=A[0];
        int start=0;
        int end=0;
        for(int i=1;i<A.length;i++)
        {
            sum_here+=A[i];
            if(sum_here>max){
                max=sum_here;
                end=i;
            }
            if(sum_here<A[i])
            {
                max=A[i];
                sum_here=A[i];
                start=i;
            }
            
        }
        long ans=0,product=0;
        for(int i=start;i<end;i++)
        {
            for(int j=i+1;j<=end;j++)
            {
               product=A[i]*A[j];
                ans+=product;
            }
        }
        return ans;
    }

    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();
    }
}