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.
// package EducationalRound88;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.StringTokenizer;
import java.util.TreeSet;

public class ProblemD {
    public static void main(String[] args)throws IOException {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        StringBuilder print=new StringBuilder();
        StringTokenizer st;
        int n=Integer.parseInt(br.readLine());
        int a[]=new int[n+1];
        st=new StringTokenizer(br.readLine());
        for(int i=1;i<=n;i++){
            a[i]=Integer.parseInt(st.nextToken());
        }
        int dp[][]=new int[n+1][61];
        for(int k[]:dp){
            Arrays.fill(k,Integer.MIN_VALUE/2);
        }
        int max=0;
        for(int i=1;i<=n;i++){
            dp[i][a[i]+30]=0;
//            System.out.println(a[i]+30);
            for(int j=0;j<=60;j++){
                int v=j-30;
                if(v>a[i]){
                    dp[i][j]=dp[i-1][j]+a[i];
                    max=Math.max(max,dp[i][j]);
                }
                else{
//                    System.out.println(j+" "+dp[i][a[i]+30]);
                    dp[i][a[i]+30]=Math.max(dp[i][a[i]+30],dp[i-1][j]+v);
                    max=Math.max(max,dp[i][a[i]+30]);
                }
            }
            max=Math.max(max,dp[i][a[i]+30]);
//            print(dp[i]);
        }
//        for(int j=0;j<=60;j++){
//            max=Math.max(max,dp[n][j]);
//        }
//        System.out.println(dp[1][35]);
        System.out.println(max);
    }
    public static void print(int a[]){
        for(int i=0;i<a.length;i++){
            System.out.print(a[i]+" ");
        }
        System.out.println();
    }
}
