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;
        int[] B = new int[n*(n-1)/2];
        int[] f = new int[n*(n-1)/2];
        int[] l = new int[n*(n-1)/2];
        int cnt = 0;
        for(int i=0; i < n; i++){
            for(int j=i+1; j < n; j++){
                B[cnt] = A[i]*A[j];
                f[cnt] = i;
                l[cnt] = j;
                cnt++;
            }
        }
        long sum = maxSumSubArray(B,f,l);
        return sum;
        
        // Return the largest value of any of A's nonempty subarrays.
    }
    private static long maxSumSubArray(int[] arr,int[] f,int[] l)
 {
  int currentStart = 0;
  int currentEnd = 0;
  long currentSum = 0;
  int maxStart = 0;
  int maxEnd = 0;
  long maxSum = 0;
  while (currentEnd != arr.length)
  {
   currentSum += arr[currentEnd];
   if (currentSum > maxSum)
   {
    maxSum = currentSum;
    maxStart = f[currentStart];
    maxEnd = l[currentEnd];
   }
   if (currentSum <= 0)
   {
    currentStart = l[currentEnd] + 1;
    currentSum=0;
   }
   currentEnd = currentEnd + 1;
  }
  //System.out.println("Maximum sum = " + maxSum);
  //System.out.println("Indexes (" + maxStart + "," + maxEnd + ")");
 
    return maxSum;
}

    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();
    }
}