import java.util.Scanner;

public class Solution {
	
	static long largestValue(int[] A) {
		int N = A.length;
		long[] cumul = new long[N];
		long sum = 0;
		for (int i = 0; i < N; i++) {
			sum += A[i];
			cumul[i] = sum;
		}
		
		long max = Integer.MIN_VALUE;
		for (int i = 0; i < N; i++) {
			int cur = 0;
			for (int j = i; j < N; j++) {
				cur += (cumul[j] - (i == 0 ? 0 : cumul[i - 1]) - A[j]) * A[j];
				if (i != j)
					max = Math.max(max, cur);
			}
		}
		return max;
    }
	
	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();
	}
}