Problem:
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Maximum Profit

You can obtain profits from foreign exchange margin transactions. For example, if you buy 1000 dollar at a rate of 100 yen per dollar, and sell them at a rate of 108 yen per dollar, you can obtain (108 - 100) × 1000 = 8000 yen.

Write a program which reads values of a currency $R_t$ at a certain time $t$ ($t = 0, 1, 2, ... n-1$), and reports the maximum value of $R_j - R_i$ where $j > i$ .

Input

The first line contains an integer $n$. In the following $n$ lines, $R_t$ ($t = 0, 1, 2, ... n-1$) are given in order.

Output

Print the maximum value in a line.

Constraints

$2 \leq n \leq 200,000$

$1 \leq R_t \leq 10^9$

Sample Input 1

6
5
3
1
3
4
3

Sample Output 1

3

Sample Input 2

3
4
3
2

Sample Output 2

-1

Solution in C# (judge verdict: Accepted)

using System;
using System.Collections.Generic;

public class test {
    static public void Main () {
        var n = int.Parse (Console.ReadLine ());
        int pre;
        List<int> a = new List<int> ();
        for (pre = 0; pre < n; pre++) {
            a.Add (int.Parse (Console.ReadLine ()));
        }
        int maxv = a[a.Count - 1] - a[0];
        int minv = a[0];
        for (int i = 1; i < n; i++) {
            maxv = Math.Max (maxv, a[i] - minv);
            minv = Math.Min (minv, a[i]);
        }

        Console.Write ("{0}\n", maxv);
    }
}