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 i,j,k,count=0;
        int size = a.length;
        int max_so_far = Integer.MIN_VALUE, max_ending_here = 0;
 
        int s=0,b=0;
        long sum=0L;
        
        for ( i = 0; i < size; i++)
        {
            
            max_ending_here = max_ending_here + a[i];
            if (max_so_far < max_ending_here)
            {    b=i;
            
             if(s==0)
             {
                 s=i;
             }
             max_so_far = max_ending_here;                                                       //  -3 7 -2 3 5 -2
           
            
            }
            
            if (max_ending_here < 0)
            {
               s=0;
                max_ending_here = 0;
            }
            
        }
        
        
        for(i=s;i<b;i++)
        {
            for(j=i+1;j<=b;j++)
            {
                sum = sum+ (long)(a[i]*a[j])  ;
            }
            
        }
        
        
      //  System.out.println(s+  " dedd "+b ); 
       // System.out.println(max_so_far +"  dcsd"+ sum ); 
        // System.out.println( sum ); 
        
       
        return sum;
    
    
    }
    
    
    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();
    }
}