Caisa solved the problem with the sugar and now he is on the way back to home. 

Caisa is playing a mobile game during his path. There are (n + 1) pylons numbered from 0 to n in this game. The pylon with number 0 has zero height, the pylon with number i (i > 0) has height hi. The goal of the game is to reach n-th pylon, and the only move the player can do is to jump from the current pylon (let's denote its number as k) to the next one (its number will be k + 1). When the player have made such a move, its energy increases by hk - hk + 1 (if this value is negative the player loses energy). The player must have non-negative amount of energy at any moment of the time. 

Initially Caisa stand at 0 pylon and has 0 energy. The game provides a special opportunity: one can pay a single dollar and increase the height of anyone pylon by one. Caisa may use that opportunity several times, but he doesn't want to spend too much money. What is the minimal amount of money he must paid to reach the goal of the game?

Input

The first line contains integer n (1 ≤ n ≤ 105). The next line contains n integers h1, h2, ..., hn (1 ≤ hi ≤ 105) representing the heights of the pylons.

Output

Print a single number representing the minimum number of dollars paid by Caisa.

Examples

Input

5
3 4 3 2 4


Output

4


Input

3
4 4 4


Output

4

Note

In the first sample he can pay 4 dollars and increase the height of pylon with number 0 by 4 units. Then he can safely pass to the last pylon.

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.PriorityQueue;
import java.util.StringTokenizer;

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
/**
 * 6
 * 1 0
 * 0 0
 * 0 0
 * 1 1
 * 0 1
 * 1 1
 *
 * @author pttrung
 */
public class B {

    public static boolean circle;
    public static int[] dp;
    public static int[] x = {0, 0, 1, -1};
    public static int[] y = {-1, 1, 0, 0};

    public static void main(String[] args) throws FileNotFoundException {
        PrintWriter out;

        Scanner in = new Scanner();
        //out = new PrintWriter(new FileOutputStream(new File("output.txt")));
        out = new PrintWriter(System.out);
        int n = in.nextInt();
        long[] data = new long[n];
        for (int i = 0; i < n; i++) {
            data[i] = in.nextInt();
        }
        long start = 0;
        long result = data[0];
        for(int i = 0; i < n - 1; i++){
            long v = data[i] - data[i + 1];
            if(start + v < 0){
                result -= (v + start);
                start = 0;
            }else{
                start += v;
            }
        }
        out.println(result);
        


        out.close();
    }

    public static long dist(int x1, int y1, int x2, int y2) {
        long x = x1 - x2;
        long y = y1 - y2;
        return x * x + y * y;
    }

    public static Line getLine(Point a, Point b) {
        int c = (a.x - b.x);
        int d = (a.y - b.y);
        if (c == 0) {
            return new Line(1, 0, -a.x);
        } else if (d == 0) {
            return new Line(0, 1, -a.y);
        } else {
            double rate = (double) (-d) / c;

            double other = ((double) rate * a.x) + a.y;
            //System.out.println(a + "|" + b + ": " + rate + " " + other);
            return new Line(rate, 1, -other);
        }
    }

    public static class Line {

        double a, b, c;

        public Line(double a, double b, double c) {
            this.a = a;
            this.b = b;
            this.c = c;
        }

        @Override
        public int hashCode() {
            int hash = 7;
            hash = 47 * hash + (int) (Double.doubleToLongBits(this.a) ^ (Double.doubleToLongBits(this.a) >>> 32));
            hash = 47 * hash + (int) (Double.doubleToLongBits(this.b) ^ (Double.doubleToLongBits(this.b) >>> 32));
            hash = 47 * hash + (int) (Double.doubleToLongBits(this.c) ^ (Double.doubleToLongBits(this.c) >>> 32));
            return hash;
        }

        @Override
        public boolean equals(Object obj) {
            if (obj == null) {
                return false;
            }
            if (getClass() != obj.getClass()) {
                return false;
            }
            final Line other = (Line) obj;
            if (Double.doubleToLongBits(this.a) != Double.doubleToLongBits(other.a)) {
                return false;
            }
            if (Double.doubleToLongBits(this.b) != Double.doubleToLongBits(other.b)) {
                return false;
            }
            if (Double.doubleToLongBits(this.c) != Double.doubleToLongBits(other.c)) {
                return false;
            }
            return true;
        }

        @Override
        public String toString() {
            return a + " " + b + " " + c;
        }
    }

    static class FT {

        int[] data;

        FT(int n) {
            data = new int[n];
        }

        void update(int index, int val) {
            // System.out.println("UPDATE INDEX " + index);
            while (index < data.length) {
                data[index] += val;
                index += index & (-index);

                //    System.out.println("NEXT " +index);
            }
        }

        int get(int index) {
            //  System.out.println("GET INDEX " + index);
            int result = 0;
            while (index > 0) {
                result += data[index];
                index -= index & (-index);
                // System.out.println("BACK " + index);
            }
            return result;
        }
    }

    public static double dist(Point a, Point b) {
        double val = (a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y);
        return Math.sqrt(val);
    }

    public static class Point {

        int x, y;

        public Point(int x, int y) {
            this.x = x;
            this.y = y;
        }

        @Override
        public String toString() {
            return x + " " + y;
        }
    }

    public static boolean nextPer(int[] data) {
        int i = data.length - 1;
        while (i > 0 && data[i] < data[i - 1]) {
            i--;
        }
        if (i == 0) {
            return false;
        }
        int j = data.length - 1;
        while (data[j] < data[i - 1]) {
            j--;
        }
        int temp = data[i - 1];
        data[i - 1] = data[j];
        data[j] = temp;
        Arrays.sort(data, i, data.length);
        return true;
    }

    public static long pow(int a, int b) {
        if (b == 0) {
            return 1;
        }
        if (b == 1) {
            return a;
        }
        long val = pow(a, b / 2);
        if (b % 2 == 0) {
            return val * val;
        } else {
            return val * val * a;
        }
    }

    public static long gcd(long a, long b) {
        if (b == 0) {
            return a;
        }
        return gcd(b, a % b);
    }

    public static long lcm(long a, long b) {
        return a * b / gcd(a, b);
    }

    static class Scanner {

        BufferedReader br;
        StringTokenizer st;

        public Scanner() throws FileNotFoundException {
            // System.setOut(new PrintStream(new BufferedOutputStream(System.out), true));
            br = new BufferedReader(new InputStreamReader(System.in));
            //  br = new BufferedReader(new FileReader(new File("output.txt")));
        }

        public String next() {

            while (st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (Exception e) {
                    throw new RuntimeException();
                }
            }
            return st.nextToken();
        }

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

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

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

        public String nextLine() {
            st = null;
            try {
                return br.readLine();
            } catch (Exception e) {
                throw new RuntimeException();
            }
        }

        public boolean endLine() {
            try {
                String next = br.readLine();
                while (next != null && next.trim().isEmpty()) {
                    next = br.readLine();
                }
                if (next == null) {
                    return true;
                }
                st = new StringTokenizer(next);
                return st.hasMoreTokens();
            } catch (Exception e) {
                throw new RuntimeException();
            }
        }
    }
}
