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 {
    static PrintWriter pw;
    static Scanner sc;
    static int ceildiv(int x, int y){
        return x%y==0? x/y: x/y+1;
    }
    static void print(boolean b){ pw.println(b?"YES":"NO");}
    static boolean test(ArrayList<Integer> list, int[] arr, int idx){
        int sum=0;
        for(int i=0; i<list.size(); i++)
            sum+=Math.abs(list.get(i)-idx);
        return sum==arr[idx];
    }
    static long kadane(int[] arr, int c){
        int[] dp=new int[arr.length];
        if(arr[0]>c){
            dp[0]=Integer.MIN_VALUE/2;
        }else{
            dp[0]=arr[0];
        }
        for(int i=1; i<arr.length; i++){
            if(arr[i]<=c){
                dp[i]=Math.max(0, dp[i-1])+arr[i];
            }else{
                dp[i]=Integer.MIN_VALUE/2;
            }
        }
        long ans=0l;
        for(int i=0; i<arr.length; i++)
            ans=Math.max(dp[i]-c, ans);
        return ans;
    }
    public static void main(String[] args) throws Exception {
        sc = new Scanner(System.in);
        pw = new PrintWriter(System.out);
        int n=sc.nextInt();
        int[] arr=sc.nextArr(n);
        long ans=0l;
        for(int i=1; i<=30; i++){
            long b=kadane(arr, i);
            ans=Math.max(ans, b);
        }
        pw.println(ans);
        pw.close();
    }
    static void printArr(int[] arr){
        for(int i=0; i<arr.length-1; i++)
            pw.print(arr[i]+" ");
        pw.println(arr[arr.length-1]);
    }
    static void printArr(long[] arr){
        for(int i=0; i<arr.length-1; i++)
            pw.print(arr[i]+" ");
        pw.println(arr[arr.length-1]);
    }
    static void printArr(Integer[] arr){
        for(int i=0; i<arr.length-1; i++)
            pw.print(arr[i]+" ");
        pw.println(arr[arr.length-1]);
    }
    static class Scanner {
        StringTokenizer st;
        BufferedReader br;
        public Scanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        }

        public Scanner(FileReader r) {
            br = new BufferedReader(r);
        }

        public String next() throws IOException {
            while (st == null || !st.hasMoreTokens())
                st = new StringTokenizer(br.readLine());
            return st.nextToken();
        }

        public int nextInt() throws IOException {
            return Integer.parseInt(next());
        }

        public long nextLong() throws IOException {
            return Long.parseLong(next());
        }

        public String nextLine() throws IOException {
            return br.readLine();
        }

        public double nextDouble() throws IOException {
            return Double.parseDouble(next());
        }

        public int[] nextArr(int n) throws IOException {
            int[] arr = new int[n];
            for (int i = 0; i < arr.length; i++)
                arr[i] = nextInt();
            return arr;
        }
        public Integer[] nextsort(int n) throws IOException{
            Integer[] arr=new Integer[n];
            for(int i=0; i<n; i++)
                arr[i]=nextInt();
            return arr;
        }
        public Pair nextPair() throws IOException{
            return new Pair(nextInt(), nextInt());
        }
        public Pair[] nextPairArr(int n, int l) throws IOException{
            Pair[] arr=new Pair[n];
            if(l==2){
                int[] a=nextArr(n), b=nextArr(n);
                for(int i=0; i<n; i++)
                    arr[i]=new Pair(a[i], b[i]);
                return arr;
            }
            for(int i=0; i<n; i++)
                arr[i]=new Pair(nextInt(), nextInt());
            return arr;
        }
        public boolean ready() throws IOException {
            return br.ready();
        }
    }
    static class Kad{
        long sum;
        int max;
        public Kad(long x, int y) {
            this.sum=x;
            this.max=y;
        }
    }
    static class Pair implements Comparable<Pair>{
        int x;
        int y;
        public Pair(int x, int y) {
            this.x=x;
            this.y=y;
        }
        public int hashCode() {
            return this.x*1000+this.y;
        }
        public int compareTo(Pair other) {
            if(this.x!=other.x)
                return this.x-other.x;
            return this.y-other.y;
        }
        public boolean equals(Object obj) {
            if (obj == null) {
                return false;
            }
            if (this.getClass() != obj.getClass()) {
                return false;
            }
            Pair p = (Pair) obj;
            if(this.x==p.x)
                return this.y==p.y;
            if(this.x==p.y)
                return this.y==p.x;
            else
                return false;
        }
        public boolean equal(Pair p){
            if(this.x==p.x)
                return this.y==p.y;
            if(this.x==p.y)
                return this.y==p.x;
            else
                return false;
        }
    }
}
