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.util.Scanner;

public class Main {

    static long[][][] aa;

    static long maxx(int[] arr,int ind,int flag,int max){
        if(ind>=arr.length){
            if(flag==2){
            return -max;}else{
                return max;
            }
        }
        if(aa[ind][max][flag]!=Integer.MIN_VALUE){
            return aa[ind][max][flag];
        }
        if(flag==0){

                if(arr[ind]<0 ){
                    return aa[ind][max][flag]= Math.max( maxx(arr,ind+1,1,-arr[ind])+arr[ind],maxx(arr,ind+1,0,max));
                }
                else{
                    return aa[ind][max][flag]=Math.max( maxx(arr,ind+1,2,arr[ind])+arr[ind],maxx(arr,ind+1,0,max) );
                }


        }
        else{
            if(flag==1) {
                if (-max < arr[ind]) {
                    if (arr[ind] < 0) {
                        return aa[ind][max][flag]= Math.max(maxx(arr, ind + 1,1,-arr[ind] )+arr[ind],max);
                    }else{
                        return aa[ind][max][flag]= Math.max(maxx(arr,ind+1,2,arr[ind])+arr[ind],max);
                    }
                }
                else{
                    return aa[ind][max][flag]= Math.max(maxx(arr,ind+1,1,max)+arr[ind],max);
                }
            }
            else{
                if(max<arr[ind]){
                    return aa[ind][max][flag]= Math.max(maxx(arr,ind+1,2,arr[ind])+arr[ind],-max);
                }else{
                    return aa[ind][max][flag]= Math.max(maxx(arr,ind+1,2,max)+arr[ind],-max);
                }
            }
        }
    }



    public static void main(String[] args) {
        Scanner scanner=new Scanner(System.in);
        int n=scanner.nextInt();
        int arr[]=new int[n];
        aa=new long[n][31][3];
        int tot=0;
        for(int j=0;j<n;j++){
            arr[j]=scanner.nextInt();
            if(arr[j]<0){tot++;}
            for(int i=0;i<31;i++){
                for(int k=0;k<3;k++){
                    aa[j][i][k]=Integer.MIN_VALUE;
                }
            }
        }
        if(tot==n){
            System.out.println(0);
        }else{
            System.out.println(maxx(arr,0,0,0));
        }
    }

}
