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 Solution {
	static Scanner sc=new Scanner(System.in);
	static PrintWriter out=new PrintWriter(System.out);
	//Main
	public static void main(String args[]) {
		int test=1;
		//test=sc.nextInt();
		while(test-->0) {
			int n=sc.nextInt(),a[]=new int[n];
			for(int i=0;i<n;i++) a[i]=sc.nextInt();
			int dp[][]=new int[n][31],tp[][]=new int[n][31];
			for(int j=Math.max(a[0],0);j<=30;j++)dp[0][j]=a[0];
			for(int j=Math.max(a[n-1],0);j<=30;j++) tp[n-1][j]=a[n-1];
			for(int i=1;i<n;i++) {
				for(int j=Math.max(0, a[i]);j<31;j++) {
					dp[i][j]=Math.max(a[i], a[i]+dp[i-1][j]);
				}
			}
			for(int i=n-2;i>=0;i--) {
				for(int j=Math.max(0, a[i]);j<31;j++) {
					tp[i][j]=Math.max(a[i],a[i]+tp[i+1][j]);
				}
			}
			int ans=0;
			for(int i=0;i<n;i++) {
				if(a[i]<0) continue;
				int left=0,right=0;
				if(i-1>=0) left=Math.max(0, dp[i-1][a[i]]);
				if(i+1<n)right=Math.max(0, tp[i+1][a[i]]);
				ans=Math.max(ans, left+right);
			}
			out.println(ans);
		}
		out.flush();
		out.close();
	}
}
