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

public class Solution {

    static long largestValue(int[] A) {
        long ret = 0;
        for(int i = 0; i < A.length; i++){
            long currSum = 0;
            long currValue = 0;
            for(int j = i; j < A.length; j++){
                currValue += currSum * A[j];
                currSum += A[j];
                ret = Math.max(ret, currValue);
            }
            
        }
        
        return ret;
    }

    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();
    }
}