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.*;
import java.math.*;
import java.awt.Point;
 
public class Main {
	//static final long MOD = 998244353L;
	//static final long INF = 1000000000000000007L;
	static String letters = "abcdefghijklmnopqrstuvwxyz";
	static final long MOD = 1000000007L;
	static final int INF = 1000000007;
	
	public static void main(String[] args) {
		FastScanner sc = new FastScanner();
		PrintWriter pw = new PrintWriter(System.out);
		
		int N = sc.ni();
		int[] nums = new int[N+2];
		SegmentTree numST = new SegmentTree(N+2);
		for (int i = 1; i <= N; i++) {
			nums[i] = sc.ni();
			numST.update(0, 0, N+1, i, nums[i]);
		}
		SegmentTree rightST = new SegmentTree(N+2);
		int[] rightPref = new int[N+2];
		for (int i = 1; i <= N; i++) {
			rightPref[i] = rightPref[i-1]+nums[i];
			rightST.update(0, 0, N+1, i, rightPref[i]);
		}
		int[] leftPref = new int[N+2];
		SegmentTree leftST = new SegmentTree(N+2);
		for (int i = N; i >= 1; i--) {
			leftPref[i] = leftPref[i+1]+nums[i];
			leftST.update(0, 0, N+1, i, leftPref[i]);
		}
		
		int ans = 0;
		for (int i = 1; i <= N; i++) {
			if (nums[i] <= 0) continue;
			//binary search to find the leftmost point that is <= nums[i]
			int low = 1;
			int high = i;
			while (low < high) {
				int med = (low+high)/2;
				if (numST.query(0, 0, N+1, med, i) == nums[i]) {
					high = med;
				} else {
					low = med+1;
				}
			}
			
			int L = low;
			
			//binary search to find the rightmost point that is <= nums[i]
			low = i;
			high = N;
			while (low < high) {
				int med = (low+high+1)/2;
				if (numST.query(0, 0, N+1, i, med) == nums[i]) {
					low = med;
				} else {
					high = med-1;
				}
			}
			
			int R = low;
			
			int add1 = leftST.query(0, 0, N+1, L, i)-leftPref[i];
			int add2 = rightST.query(0, 0, N+1, i, R)-rightPref[i];
			ans = Math.max(ans,add1+add2);
		}
		pw.println(ans);
		
		pw.close();
	}
	
	static class SegmentTree {
		public int[] tree;
		public int N;

		//Zero initialization
		public SegmentTree(int n) {
			N = n;
			tree = new int[4*N+1];
		}
		
		public int query(int treeIndex, int lo, int hi, int i, int j) {
			// query for arr[i..j]
			if (lo > j || hi < i)
				return 0;
			if (i <= lo && j >= hi)
				return tree[treeIndex];
			int mid = lo + (hi - lo) / 2;

			if (i > mid)
				return query(2 * treeIndex + 2, mid + 1, hi, i, j);
			else if (j <= mid)
				return query(2 * treeIndex + 1, lo, mid, i, j);

			int leftQuery = query(2 * treeIndex + 1, lo, mid, i, mid);
			int rightQuery = query(2 * treeIndex + 2, mid + 1, hi, mid + 1, j);

			// merge query results
			return merge(leftQuery, rightQuery);
		}

		public void update(int treeIndex, int lo, int hi, int arrIndex, int val) {
			if (lo == hi) {
				tree[treeIndex] = val;
				return;
			}

			int mid = lo + (hi - lo) / 2;

			if (arrIndex > mid)
				update(2 * treeIndex + 2, mid + 1, hi, arrIndex, val);
			else if (arrIndex <= mid)
				update(2 * treeIndex + 1, lo, mid, arrIndex, val);

			// merge updates
			tree[treeIndex] = merge(tree[2 * treeIndex + 1], tree[2 * treeIndex + 2]);
		}

		public int merge(int a, int b) {
			return Math.max(a,b);
		}
	}
	
 
	public static long dist(long[] p1, long[] p2) {
		return (Math.abs(p2[0]-p1[0])+Math.abs(p2[1]-p1[1]));
	}
	
	//Find the GCD of two numbers
	public static long gcd(long a, long b) {
		if (a < b) return gcd(b,a);
		if (b == 0)
			return a;
		else
			return gcd(b,a%b);
	}
	
	//Fast exponentiation (x^y mod m)
	public static long power(long x, long y, long m) { 
		if (y < 0) return 0L;
		long ans = 1;
		x %= m;
		while (y > 0) { 
			if(y % 2 == 1) 
				ans = (ans * x) % m; 
			y /= 2;  
			x = (x * x) % m;
		} 
		return ans; 
	}
	
	public static int[] shuffle(int[] array) {
		Random rgen = new Random();
		for (int i = 0; i < array.length; i++) {
		    int randomPosition = rgen.nextInt(array.length);
		    int temp = array[i];
		    array[i] = array[randomPosition];
		    array[randomPosition] = temp;
		}
		return array;
	}
	
	public static long[] shuffle(long[] array) {
		Random rgen = new Random();
		for (int i = 0; i < array.length; i++) {
		    int randomPosition = rgen.nextInt(array.length);
		    long temp = array[i];
		    array[i] = array[randomPosition];
		    array[randomPosition] = temp;
		}
		return array;
	}
	
	public static int[][] shuffle(int[][] array) {
		Random rgen = new Random();
		for (int i = 0; i < array.length; i++) {
		    int randomPosition = rgen.nextInt(array.length);
		    int[] temp = array[i];
		    array[i] = array[randomPosition];
		    array[randomPosition] = temp;
		}
		return array;
	}
	
    public static int[][] sort(int[][] array) {
    	//Sort an array (immune to quicksort TLE)
 
		Arrays.sort(array, new Comparator<int[]>() {
			  @Override
        	  public int compare(int[] a, int[] b) {
				  return a[0]-b[0]; //ascending order
	          }
		});
		return array;
	}
    
    public static long[][] sort(long[][] array) {
    	//Sort an array (immune to quicksort TLE)
		Random rgen = new Random();
		for (int i = 0; i < array.length; i++) {
		    int randomPosition = rgen.nextInt(array.length);
		    long[] temp = array[i];
		    array[i] = array[randomPosition];
		    array[randomPosition] = temp;
		}
		Arrays.sort(array, new Comparator<long[]>() {
			  @Override
        	  public int compare(long[] a, long[] b) {
				  if (a[0] < b[0])
					  return -1;
				  else
					  return 1;
	          }
		});
		return array;
	}
    
    static class FastScanner { 
        BufferedReader br; 
        StringTokenizer st; 
  
        public FastScanner() { 
            br = new BufferedReader(new InputStreamReader(System.in)); 
        } 
  
        String next() { 
            while (st == null || !st.hasMoreElements()) { 
                try { 
                    st = new StringTokenizer(br.readLine());
                } catch (IOException  e) { 
                    e.printStackTrace(); 
                } 
            } 
            return st.nextToken(); 
        }
        
        int ni() { 
            return Integer.parseInt(next()); 
        }
  
        long nl() { 
            return Long.parseLong(next()); 
        } 
  
        double nd() { 
            return Double.parseDouble(next()); 
        } 
  
        String nextLine() {
            String str = ""; 
            try { 
                str = br.readLine(); 
            } catch (IOException e) {
                e.printStackTrace(); 
            } 
            return str;
        }
    }
}