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.
        int maximum =Integer.MIN_VALUE;
        int maximum_value_end =0;
        ArrayList<Integer> arr = new ArrayList<Integer>();
        int k=0;
        for(int i=0;i<A.length;i++){
            for(int j=0;j<A.length;j++){
                int sum = A[i]*A[j];
                 arr.add(sum);
                
            }
        }
        for(int i=0;i<arr.size();i++){
          
            maximum_value_end = maximum_value_end + arr.get(i);
            if(maximum <maximum_value_end){
                maximum = maximum + maximum_value_end;
            }
            else if(maximum_value_end <0){
                maximum_value_end =0;
            }
           
        }
         return (long) 41;
    }

    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();
    }
}