Alice and Bob are playing yet another card game. This time the rules are the following. There are n cards lying in a row in front of them. The i-th card has value a_i. 

First, Alice chooses a non-empty consecutive segment of cards [l; r] (l ≤ r). After that Bob removes a single card j from that segment (l ≤ j ≤ r). The score of the game is the total value of the remaining cards on the segment (a_l + a_{l + 1} + ... + a_{j - 1} + a_{j + 1} + ... + a_{r - 1} + a_r). In particular, if Alice chooses a segment with just one element, then the score after Bob removes the only card is 0.

Alice wants to make the score as big as possible. Bob takes such a card that the score is as small as possible.

What segment should Alice choose so that the score is maximum possible? Output the maximum score.

Input

The first line contains a single integer n (1 ≤ n ≤ 10^5) — the number of cards.

The second line contains n integers a_1, a_2, ..., a_n (-30 ≤ a_i ≤ 30) — the values on the cards.

Output

Print a single integer — the final score of the game.

Examples

Input


5
5 -2 10 -1 4


Output


6


Input


8
5 2 5 3 -30 -30 6 9


Output


10


Input


3
-10 6 -15


Output


0

Note

In the first example Alice chooses a segment [1;5] — the entire row of cards. Bob removes card 3 with the value 10 from the segment. Thus, the final score is 5 + (-2) + (-1) + 4 = 6.

In the second example Alice chooses a segment [1;4], so that Bob removes either card 1 or 3 with the value 5, making the answer 5 + 2 + 3 = 10.

In the third example Alice can choose any of the segments of length 1: [1;1], [2;2] or [3;3]. Bob removes the only card, so the score is 0. If Alice chooses some other segment then the answer will be less than 0.
import java.io.*;
import java.util.*;
public class Main
{
	final int maxn=30,zero=maxn;
	private void solve()throws Exception
	{
		int n=nextInt();
		int a[]=new int[n+1];
		for(int i=1;i<=n;i++)
			a[i]=nextInt();
		//dp[i][j] is the max score of subarray ending at i with max value j
		int dp[][]=new int[n+1][zero+maxn+1];
		int inf=1<<30;
		for(int i=0;i<=n;i++)
			Arrays.fill(dp[i],-inf);
		int ans=0;
		for(int i=1;i<=n;i++)
			for(int j=-maxn;j<=maxn;j++)
			{
				if(j<a[i])
					continue;
				if(j==a[i])
				{
					dp[i][zero+j]=0;
					for(int k=-maxn;k<=a[i];k++)
						if(dp[i-1][zero+k]!=-inf)
							dp[i][zero+j]=Math.max(dp[i][zero+j],dp[i-1][zero+k]+k);
				}
				else
					dp[i][zero+j]=dp[i-1][zero+j]==-inf?-inf:dp[i-1][zero+j]+a[i];
				ans=Math.max(ans,dp[i][zero+j]);
			}
		out.println(ans);
	}

	 
	///////////////////////////////////////////////////////////

	public void run()throws Exception
	{
		br=new BufferedReader(new InputStreamReader(System.in));
		st=null;
		out=new PrintWriter(System.out);

		solve();
		
		br.close();
		out.close();
	}
	public static void main(String args[])throws Exception{
		new Main().run();
	}
	BufferedReader br;
	StringTokenizer st;
	PrintWriter out;
	String nextToken()throws Exception{
		while(st==null || !st.hasMoreTokens())
		st=new StringTokenizer(br.readLine());
		return st.nextToken();
	}
	String nextLine()throws Exception{
		return br.readLine();
	}
	int nextInt()throws Exception{
		return Integer.parseInt(nextToken());
	}
	long nextLong()throws Exception{
		return Long.parseLong(nextToken());
	}
	double nextDouble()throws Exception{
		return Double.parseDouble(nextToken());
	}
}