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

public class Solution {

   
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int[] A = new int[n];
        int b[]=new int[100000000];
        int a[]=new int[100000000];
        int nlen=0;
        int plen=0;
        for(int i = 0; i < n; i++){
            A[i] = in.nextInt();
            if(A[i]<=0){
                 b[i]=A[i];
                nlen++;
            }
            else{
                a[i]=A[i];
                plen++;
            }
                 
        }
        
        int min=1000000;
        
        for(int m=0;m<nlen;m++){
            if(min<b[m])
                min=b[m];
        }
        

        
        long count=0;
        long sum1=0,sum2=0;
        long result;
        
        for(int k=0;k<plen-1;k++){
            for(int l=k+1;k<plen;k++)
                sum1=sum1+(a[k]*a[l]);
                sum2=sum2+(a[k]*min);
        }
        
        result=sum1+sum2;
        
        
        
                
        
        
        
        
        System.out.println(result);
        in.close();
    }
}