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

public class Solution {

    static void msm(int a[], int size)
    {
        long max_so_far = Long.MIN_VALUE,
        max_ending_here = 0;
        int start = 0;
        int end = 0;
        int s = 0;
 
        for (int i = 0; i < size; i++) 
        {
            max_ending_here += a[i];
 
            if (max_so_far < max_ending_here) 
            {
                max_so_far = max_ending_here;
                start = s;
                end = i;
            }
 
            if (max_ending_here < 0) 
            {
                max_ending_here = 0;
                s = i + 1;
            }
        }
        lvm(a, start, end, max_so_far);
        
       
    }
    
    
    static void lvm(int a[], int s, int  e, long sum) {
        // Return the largest value of any of A's nonempty subarrays.
    
        long asm = sum * sum;
        
        long isqsum = 0;
    for (int i = s; i <= e; i++)
        isqsum += a[i]*a[i];
    
        
       long ans =  (asm - isqsum)/2;

    System.out.print(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();
        }
          msm(A, n);
      
        in.close();
    }
}